at least in PA this is how it works(at least This is how I think it works)
You are given a limit of 6 ducks with qualifiers for specific species or sex. Like 4 mallards, of which only 2 hens, or 2 wood ducks, or 1 pintail, etc
SO, you could shoot, in one day, 4 drakes and 2 woodies. BUT species that are not listed example teal or gadwall, you can shoot up to the daily limit of those. cannot exceed total daily limit
For example, you could shoot 4 teal and 2 woddies, or 6 teal, or 3 gadwall and 3 teal or 2 hen mallards, 2 woodies, 1 pintail & 1 can.
Hope this helps,