Ghosting (doubble line) in engraving only in the middle

Hi, when I try to engrave a text there is a double (ghosting) line in the middle of the object.

I have Ruida 644XS
Speed I am using is 400 and power 20%

Any idea what could fix this?

Does it make a difference if you burn it on a different area of your bed?

Does your machine do the same thing with a different file?

based on just the picture I would guess an alignment issue or bent gantry, but more info would help.