Blue Marble installs in Custom Assets folder. If you mess with mods a lot you should know where it is located. (you can find it in the BTS root as a short cut but it is actually located in Documents)
Mods installed into CA will be in effect for any game you run, i.e., it is just there, except in cases where "standalone" mods are set to ignore custom assets.
Not familiar with mods like super spies, but my assumption due to the very focused/specific nature of the mod is that it is a mod component that gets installed into CA. In other words, it is not a "standalone" mod. Therefore, it's possible that Blue Marble overwrote the mod files..not sure though as the BM seems to me that it would not touch those types of files. OR you simply did something wrong with the installation of one or the other. BM install is pretty hard to mess up though.
(FYI - what I mean by "standalone mods" are full modpacks that get installed in a separate mod folder as opposed to CA folder. You have to load standalone mods - or set them to load automatically)
If you want Blue marble and other cool graphics, plus UI enhancements, I recommend simply using the BAT mod -best unaltered gameplay mod out there.
I'd be careful just randomly installing these small mods just cause you think they sound cool. Some me be old and outdated - no clue as I never use them. (Blue Marble is a very good mod that a lot of folks use, so there no problem with it. The issue probably lies somewhere between trying to install funky mods to just not knowing what you are doing.
If you want to mess around with mods a lot, especially mod components (basically mod parts) then educate yourself. Go to the Mods forum and ask questions and look at mod tutorials.
Ofc, imo messing about with all these little mods is keeps you spending more time on what is really fun - the actual game. There are plenty of full mods that give you a lot of what you want without actually having to do anything or mucking things up.
