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

Former-commit-id: f4c508d3a8e5870cd4fd140378ae4230861d32d0
Former-commit-id: bbc0a2a94ff0706ccba51060e7763dd59073dde9
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox