Hello!
Whenever I encounter a pokemon that I already own the pokeball icon near the pokemon name is not showing (at least on legacy maps). And not for all the pokes. For some I still see the pokeball icon. Due to that I have caught quite some pokemons I already have. I have this problem for a while now.. just didn't post because i thought that the problem is global, but I guess it's not because the people I asked if they have the same problem don't have this problem.
Cheers!