The same filter option, such as Sauna or Pool, can appear twice in your website’s search filters. There are two separate causes.
Two similar tags in your PMS. If your PMS has two distinct tags with slightly different names, such as ‘Pool’ and ‘Pools’, the site treats them as separate filters. To fix this, consolidate to a single tag in your PMS and retag any affected listings. The site collapses them to one filter on the next sync.
A group tag and an amenity with the same name. The search filter system pulls from both group tags and individual listing amenity fields, so a ‘[g] Sauna’ tag alongside a ‘Sauna’ amenity produces two entries. Renaming the tag alone does not fix this. Instead, remove the group tag where the amenity already covers it, or contact support to adjust which filter sources the search uses.
Before you delete a group tag. Check with support first, as some group tags power collection pages that your site links to.