Since your test methods typically don't have different signatures (I guess they will seldom have parameters), you need a different way to distinguish them. As long as the WhenSomeScenario part is different for different overloads, you don't have to provide any special measures:
MyMethod_Returns0_WhenCalledWith1 // testing MyMethod(int)
MyMethod_Returns0_WhenCalledWith1_2 // testing MyMethod(int,int)
does it.
If that does not work in specific cases, because you have a more abstract scenarios to test, where the names don't reflect the input parameters directly, you need something like
NameOfMethodSignaturecode_ExpectedBehavior_WhenSomeScenario
You still have to decide what you fill in for the Signaturecode, depends a little bit on your personal taste. When you are willing to use very long method names, you could use just add a concatenation of the typenames, like
MyMethodInt_Returns0_WhenCalledBeforeInitialization // testing MyMethod(int)
MyMethodIntInt_Returns0_WhenCalledBeforeInitialization // testing MyMethod(int,int)
If you think the method names become too long that way, you have to use some kind of shortage for the typenames (for example, analogous to the shortages in Hungarian notation). What I would avoid is to use some kind of index 1,2,3,... to distinguish the test methods, this gives you no clue which test method is for which overload.