It seems this sofer corrected the vav in'uvekumecha'(line 5), but he didn't make a second sirtut before writing the word again.
Mishnat Hasofer (3,21) writes about the machkloket on that (Bnei Yonah x Achronim).
If this mezuza can be kasher bediavad, I should anyway make the sirtut now. But the vav is upwards in relation to the sirtut level, and the sirtut could also take its rosh out by making some hefsek. What to do then?.