Shadowing/printing two of the image

[TGLucie]

I have a mini laser engraving machine, just for home use, but it seems to be that when printing towards the right-hand side, the image is becoming thicker and eventually separating so it looks like there is double of the image, a few mm in difference/apart. ~Any ideas on why this could be? Changed lasers and happens with both and also there are some points where a whole line is not lasered like the others and comes out very faint.