help with colliders not working

hello all. i have a character witha circle collider(all 2d) then a platform with box collider. it was all working fine. ever since i imported 2 packages one called simple 2d enemy KI and the other is the lite version of platformer pro. now every time i press play no colliders actually work. they have their respective colliders and or rigid bodies and everything has been the same except importing the packages. now they just fall through. i am getting a error i havent gotten before. this is it Default GameObject Tag: Player already registered. please help i cant figure it out.

Access your Tags & Layers by one of the following ways:

  • Menu Bar: Edit > Project Settings > Tags and Layers

  • Click an item in the hierarchy, click the Tag combo box on the object in the Inspector, select Add Tag… from the combo box.

You should see all your tags for your project there.

where is the second player tag. i am a little new