I am doing an Egypt-themed map, but
@UKCS-Alias has already made an Egypt-themed MvM map, and yet I'm still doing an Egypt-themed MvM map...
Valve made a halloween themed MvM map. and my first MvM map was halloween aswel.
Its perfectly fine to have multiple maps with the same sort of looks. You dont hear me complain about decoy and coaltown (common desert), or downtown and mannhattan (city), or oilrig and mannworks (facility), yucatan and tropics (mayan), normandy and overlord (invasion).
Similar themes just confirms that people like a theme so much they are willing to make a map in such theme. It doesnt even matter if the quality of the map is excelent (although we prefer that
). Dedication to your work is what can drive you to finish the work. People like variety. If that occasionaly means a lesser quality map, its fine. As long as your map makes players happy that they play it, you have succeeded at mapping (at which point the drive can be to improve and make an even more awesome map).