C-FMMX is a Bombardier registration number and has been used multiple times.
The aircraft you mention, C-FMMX s/n 7056 is a 100LR and still in service with Skywest A/L as N409SW.
The second aircraft C-FMMX s/n 7439 is a 200LR also ex- D-ACHG, and
by your location, I'll assume your aware is now Rwandan registered as
9XR-WA of Rwanda Express.
C-FMMX has also been used on s/n 7026, 7116, 7131, 7146, 7161, 7176, 7281,
7371, 7461, 7491, 7521, 7551, 7611, 7641, 7671, 7701, 7731, 7761, 7791,
7821, 7851, 7911, 7941, 7971.