The 4 pixel skin arm do something weird on the bottom of the hand

Every time I have a skin with something on the arms (like my onesie skin or something with a jacket) part of the skin goes onto the bottom of the arm (the little square part). It make the skin look messed up or sloppy.

What I expected to happen was...:
I expected my skin to work like a regular skin

What actually happened was...:
Some other part of the skin was moved to the bottom of the hand to I guess make it 4 pixel?

Steps to Reproduce:
1. Pick a skin with something on the arms, such as sleeves of a jacket or onesie skin.
2. download the file or if chosing from a webite click the button that would update to your skin.
3. Update the skin, like you regularly would... but choose the 4 pixel arms
4. Restart minecraft launcher or launch a new one, go to single player or multi, get into F5 and look at your hands

A picture of my onesie skin is added, the chat is in the way but you can see that another color of the skin was put on the bottom of my hands which makes it look bad. This has happened with past skins but I thought it would've been fixed or brought up. I don't know if this is considered a bug or not but no one has told me how to fix it.