diff --git a/main/api/contacts/index.ts b/main/api/contacts/index.ts
index 07de7294..459595a3 100644
--- a/main/api/contacts/index.ts
+++ b/main/api/contacts/index.ts
@@ -34,11 +34,98 @@ const schema: Schema<{
   },
 };
 
-export const store = new Store({ schema, name: "contacts" });
+class ContactsUtil {
+  store = new Store({ schema, name: "contacts" });
+  contactsByAddress: Map<string, Contact> = new Map();
+
+  constructor() {
+    this.init();
+  }
+
+  init() {
+    const contacts = this.store.get("contacts", []);
+    const deduped = contacts.filter((contact) => {
+      if (this.contactsByAddress.has(contact.address)) {
+        return false;
+      }
+      this.contactsByAddress.set(contact.address, contact);
+      return true;
+    });
+    this.store.set("contacts", deduped);
+  }
+
+  getContacts() {
+    return this.store.get("contacts", []);
+  }
+
+  getContactByAddress(address: string) {
+    return this.contactsByAddress.get(address) ?? null;
+  }
+
+  addContact({ name, address }: { name: string; address: string }) {
+    if (this.contactsByAddress.has(address)) {
+      throw new Error("DUPLICATE_CONTACT_ERROR");
+    }
+
+    const contacts = this.getContacts();
+
+    contacts.push({
+      id: uuidv4(),
+      name,
+      address,
+      order: contacts.length,
+    });
+
+    this.store.set("contacts", contacts);
+
+    return contacts;
+  }
+
+  editContact({
+    id,
+    name,
+    address,
+  }: {
+    id: string;
+    name: string;
+    address: string;
+  }) {
+    const contacts = this.getContacts();
+    const index = contacts.findIndex((contact) => contact.id === id);
+
+    if (index > -1) {
+      contacts[index] = {
+        id,
+        name,
+        address,
+        order: contacts[index].order,
+      };
+      this.store.set("contacts", contacts);
+    }
+
+    return contacts;
+  }
+
+  deleteContact(id: string) {
+    const contacts = this.getContacts();
+    const index = contacts.findIndex((contact) => contact.id === id);
+
+    if (index > -1) {
+      const contact = contacts[index];
+      this.contactsByAddress.delete(contact.address);
+      contacts.splice(index, 1);
+      this.store.set("contacts", contacts);
+    }
+
+    return contacts;
+  }
+}
+
+const contactsUtil = new ContactsUtil();
 
 export const contactsRouter = t.router({
   getContacts: t.procedure.query(async () => {
-    return store.get("contacts", []);
+    return contactsUtil.getContacts();
   }),
   getContactByAddress: t.procedure
     .input(
@@ -47,11 +134,7 @@ export const contactsRouter = t.router({
       }),
     )
     .query(async (opts) => {
-      const contacts = store.get("contacts", []);
-      return (
-        contacts.find((contact) => contact.address === opts.input.address) ??
-        null
-      );
+      return contactsUtil.getContactByAddress(opts.input.address);
     }),
   addContact: t.procedure
     .input(
@@ -61,15 +144,7 @@ export const contactsRouter = t.router({
       }),
     )
     .mutation(async (opts) => {
-      const contacts = store.get("contacts", []);
-      contacts.push({
-        id: uuidv4(),
-        name: opts.input.name,
-        address: opts.input.address,
-        order: contacts.length,
-      });
-      store.set("contacts", contacts);
-      return contacts;
+      return contactsUtil.addContact(opts.input);
     }),
   editContact: t.procedure
     .input(
@@ -80,22 +155,7 @@ export const contactsRouter = t.router({
       }),
     )
     .mutation(async (opts) => {
-      const contacts = store.get("contacts", []);
-      const index = contacts.findIndex(
-        (contact) => contact.id === opts.input.id,
-      );
-
-      if (index > -1) {
-        contacts[index] = {
-          id: opts.input.id,
-          name: opts.input.name,
-          address: opts.input.address,
-          order: contacts[index].order,
-        };
-        store.set("contacts", contacts);
-      }
-
-      return contacts;
+      return contactsUtil.editContact(opts.input);
     }),
   deleteContact: t.procedure
     .input(
@@ -104,16 +164,6 @@ export const contactsRouter = t.router({
       }),
     )
     .mutation(async (opts) => {
-      const contacts = store.get("contacts", []);
-      const index = contacts.findIndex(
-        (contact) => contact.id === opts.input.id,
-      );
-
-      if (index > -1) {
-        contacts.splice(index, 1);
-        store.set("contacts", contacts);
-      }
-
-      return contacts;
+      return contactsUtil.deleteContact(opts.input.id);
     }),
 });
diff --git a/renderer/components/AddContactModal/AddContactModal.tsx b/renderer/components/AddContactModal/AddContactModal.tsx
index c036f481..6aa7eb46 100644
--- a/renderer/components/AddContactModal/AddContactModal.tsx
+++ b/renderer/components/AddContactModal/AddContactModal.tsx
@@ -54,6 +54,9 @@ const messages = defineMessages({
   address: {
     defaultMessage: "Address",
   },
+  duplicateContactError: {
+    defaultMessage: "A contact with that address already exists.",
+  },
 });
 
 type Props = {
@@ -83,6 +86,7 @@ export function AddContactModal({ isOpen, onClose }: Props) {
     isError,
     isSuccess,
     reset: resetMutation,
+    error,
   } = trpcReact.addContact.useMutation();
 
   const {
@@ -150,7 +154,11 @@ export function AddContactModal({ isOpen, onClose }: Props) {
                 {formatMessage(messages.addContactError)}
               </Heading>
               <Text fontSize="md">
-                {formatMessage(messages.somethingWentWrong)}
+                {formatMessage(
+                  error.message === "DUPLICATE_CONTACT_ERROR"
+                    ? messages.duplicateContactError
+                    : messages.somethingWentWrong,
+                )}
               </Text>
             </>
           )}
diff --git a/renderer/intl/locales/en-US.json b/renderer/intl/locales/en-US.json
index badf2444..7ae98f23 100644
--- a/renderer/intl/locales/en-US.json
+++ b/renderer/intl/locales/en-US.json
@@ -445,6 +445,9 @@
   "X+BJ/8": {
     "message": "Other Assets"
   },
+  "XIdw3B": {
+    "message": "A contact with that address already exists."
+  },
   "XLvNHQ": {
     "message": "Please write down this recovery phrase and keep it in a safe place. You will need it to recover your account."
   },