OPT: remove duplicated file extension
OPT: remove duplicated file extension

Former-commit-id: c24939383d7f46bc81c88e62441861165ac790fc
Former-commit-id: 8e1fe34d7bf541a17fa59b28d35ec6e1f3fc5956
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox