Allow for multiple bindings of the same controller button, like RetroArch does?

[Apocalypse612]

Is your feature request related to a problem? Please describe.
It seems that allowing for multiple bindings does not work on RaLibRetro, and I'm not sure why. For example, I want to map my L3 to Fast Forward (Hold), but it won't let me because my controller input already has it mapped?

Describe the solution you'd like
Allow this to happen.

Describe alternatives you've considered
n/a

Additional context
n/a