Assembly LoadFrom identical Assembly not working

i load Assemblies at Runtime from different folders. I then instanciate all Types which contain a specific interface (typeof(I).IsAssignableFrom(xy))

BUT: If the Assembly containing the Interface gets loaded by mistake (because someone placed it in one of the folders), no types will get loaded. I Assume because of the mismatch with the Interface type. I dont really understand why, since the dlls are identical. Also: is there a good way to fix this problem (i can´t get the strong name without Assembly.LoadFrom)