To be honest, I'm a little confused as to how you see these pictures as similar. Gibson's Wallace is dressed in some kind of tunic or shirt with short and uncuffed sleeves, a form of splint armor, a spiky gauntlet, fallen-down socks, flowing hair, and a kilt that wraps around his legs and then up over his shoulder. By contrast, the Scotsmen in the painting by David Morier are dressed in:

• coats made of tartan wool, somewhat shorter than was fashionable around 1745, with narrow sleeves cut on the bias and buttoning at the cuffs;

• tartan waistcoats, also a bit shorter than was fashionable, some of which seem to have long, narrow sleeves (the open coat sleeve on the man with the pike seems to show something dark underneath), worn buttoned shut in front;

• white linen shirts (mostly covered by the coat and waistcoat) with long, full sleeves gathered to a band at the wrist and to a collar at the neck;

• either tartan kilts wrapped around the thighs or bias-cut tartan breeches, the kilts not continuing to be wrapped up to the shoulder, as the man with the white belt is the only one with a tartan sash, and it does not match his kilt;

• tartan stockings cut on the bias, probably gartered to stay up over their calves;

• and the traditional "blue bonnet" that was a stereotypical piece of Highland dress in the Early Modern period.

These are massive differences. The only similarity is that Gibson's Wallace has a kilt that covers his thighs. This costume is not accurate for any period.