@jaimebm1229 you must change the name too (snesmsu1). That line looks weird though... it starts with something double; you must have copied it wrongly.
Which extension do msu1 games have? What’s the launcher? You‘ll need to change that too.
What happen when you edit metadata on the gane you want to start and you try to force the emulator and core to libretro and snes9x respectively?
If the previous steps don‘t work, try adding the following lines to recalbox.conf:
snesmsu1.emulator=libretro
snesmsu1.core=snes9x
Double-check those lines are only present once in recalbox.conf.