Echoing Flemming’s advice.
In general, unless in the field, do not work directly off the camera.
Worth noting that your Canon camera may be “splitting” the files on recording internally, to match the restrictions of the camera “operating system”/software. And, that FCPX may not be able to combine the two or more files when imported directly from camera.
FCPX has been known to corrupt external media drives in the past, so when copying off the files (Full file structure), make sure to have a copy on a back-up drive, or cloud storage or similar.
As an added comment, IMHO:
FCPX in comparison to Adobe PPro, has only a limited amount of files that it likes to work with, and even then it likes to transcode your files to a new .mov format.