UV maps issue

Hi. The garment must have the other side only in places where it is visible. The uvs of this other side must be moved away from those of the front. When you have overlapping uvs while baking, the engine does not know from what side to take the data.

You must undo what Solidify modifier did ( or restart, it cannot be fixed) and close holes differently

Also, before baking textures, you must assign a rectangular template, bring uvs back to their original size, then put them in the space meant for them