Adding to what Gigan said, I fell into the same pitfall myself where my characters end up looking the same. I think if you haven’t planned to already, you should rework both of their faces.

Doesn’t have to be anything major, but small tweaks like moving the jawline, nose shape, eye size/shape, etc all add up quickly.

Same goes for proportions. You have a solid base to work off of, so maybe try making one slightly taller. Maybe one of them has a longer upper torso while the other a longer lower torso. Different size heads, hairlines, etc. I don’t think this would require and major changes since again you have the foundation right.