Yes, it is.
“loosing” : “loose” :: ”losing” (the verb form, not the adjective) : “lose”
If you understand mistakenly using “loose” in place of “lose” you should be equally able to understand using the gerund or present participle of “loose” in place of the gerund or present participle of “lose” (or the identically-spelled adjective), with the same single-“o” insertion transforming one valid English word to another.
