Preparation table fields 'taxonlist__name' and 'taxonlist__frequency' not filtering properly

[enmust]

@ollehints @urtson
Is it possible to make the first link work like the second one.
https://api.arendus.geokogud.info/preparation/?paginate_by=30&page=1&order_by=-id&distinct=true&taxonlist__name__icontains=Ramphoprion%20gotlandensis&taxonlist__frequency__gt=3

https://api.arendus.geokogud.info/taxon_list/?paginate_by=30&page=1&distinct=true&name__icontains=Ramphoprion%20gotlandensis&frequency__gt=3

The first one doesn't filter properly.
If frequnecy is greater than 3 then this should show only one result.
http://arendus.geokogud.info/preparation?sample_number_1=1&sample_number=&locality_1=1&locality=&stratigraphy_1=1&stratigraphy=&agent_1=1&agent=&taxon_1=1&taxon=Ramphoprion%20gotlandensis&frequency_1=7&frequency=3&currentTable=preparation&maxSize=5&sort=id&sortdir=DESC