noob help

[BULLSHOCK]

ok...ive just started modding...i got the banshee into foundation...changed projectiles and all that kind of stuff...but im confused a little bit here

every one talks about specific signatures for specific maps...i know they exist...but when i fix the ecryption in dothalo, it says new signature...

so my question is, what is the difference if you sign your map with the original signature, than if you sign it with a new one?