Hi Paul
You can use a 5/8" router bit (or a 1/2" one if you don't have a 5/8" bit) and just move the jig over just a bit and reclamp it down.
This is what I would do to fix this type of error, make the 1st 5/8" slot then clamp a setup block down, then unclamp the jig and put a metal ruler (on it's side) that's about 1/32" thick, right next (in front) of the setup block then reclamp the jig down and make the 2nd pass.
Bj
