If you look at it closely, you have no right to an exchange. If you had bought 2 at the same time, both doors would probably be the same. However, since deviations always occur in production (even with car paint, small color differences are noticeable, but only to an experienced professional), especially with glass and paper, it is better to always buy the quantity that you actually need in the end.
Color deviations occur in paper, for example:
A young tree is lighter than an old tree, for example. Therefore, there are color differences in the paper.
With glass, it is similar, except that it is recycled glass, color variations occur again and again. Sometimes even to the extent that the glass has a greenish tint, or worse, a brownish tint.
That is the theory.
If I were you:
Pack up the glass door, take the receipt with you, and return it. With the note that this door has a brown or greenish tint in the glass. Within the 3-month period, there should be no problems with the exchange.