Win 7 64 bit
Geforce GTX 960
Selecting doubled up loop (same vertex positions) fails
create a cube (or just use the default one)
go to Edit Mode
set to Edge Loops charing the exact same position (e.g. split one loop by hitting "V", or shift the second loop to the exact same position of the first one)
try to select each loop seperatly (in 2.74 and before this works by Alt + Shift + RMB)
For me it does not work no more in 2.75a. Only one of booth loops can be selected.