num_classes not having an effect when training on custom data

[picosankaricpp]

I've changed custom_detection.yml to have
num_classes: 2 # your dataset classes
remap_mscoco_category: False

I'm trying to train on custom data with one class. I train using this command: $env:CUDA_VISIBLE_DEVICES="0"; python train.py -c configs/dfine/custom/objects365/dfine_hgnetv2_s_obj2custom.yml --use-amp --seed=0 -t dfine_s_obj2coco.pth.
When I export the model to onnx, it outputs confidence scores for 300 classes. Is this expected or am I missing something in my training?