I've dealt with old stuff my entire life
So, depending on your expectations (and some aren't happy unless everything perfectly matches), make your new door obvious
! Like you did it on purpose:
Move the top door down to the bottom.
Buy/find/make a picture frame door, paint
it purple(!) and put a favorite picture in the frame.
Cut a piece of wood to size, cover with batting for a pin cushion, wrap in contrasting upholstery fabric. Use this door to hang notes, pictures, etc.
You get the idea... have fun with it!