custom armor model texture not applying correctly (double texturing)

Upon making a custom model for armor, I noticed that the texture did not apply correctly. the helmet is 10x 10x 10x (standard size).

The highlighted section is the part of the texture that is double filling (filling the upper part of the helmet, right side as well as the bottom portion of the back part. the issue is that it should only be filling the back part of the helmet).

I have also searched for a solution on other forum threads, however, every other answer that I applied to this issue failed to resolve this problem. A swift and thorough response would greatly be appreciated.