Water prop does not "like" Subdivision nor Tessellation when character is submerged. Switch to Original and odd, double reflection would be gone.
For outfit it's sort of an opposite. For bra and panties leave it as subdivided.

Character is Subdivided, outfit is Subdivided
76% of original size (was 662x19) - Click to enlarge


Character is Subdivided, outfit is Original (looks like this is how you currently have it in your project)
76% of original size (was 662x19) - Click to enlarge


Character is Original, Outfit is Original
76% of original size (was 662x19) - Click to enlarge

Character is Original, Outfit is Subdivided (best)
76% of original size (was 662x19) - Click to enlarge


Update: I have noticed the bra and panties I used had a Displacement map. If I delete that map, the Original setting has to be used for outfit as well.
Still, the reflection is not 100% accurate, when character is half submerged into the water. Teeth could be seen in the reflection at some camera angles.
So you have to play with water settings and camera angles for the best visual as well.