MMT?

I've obtained two almost unused razors- After marking the edge and the spine I lapped each on the DMT 8k. The markings came off unevenly on the spine and the edge of both. Is the next step grinding down the edge and spine until the markings come off evenly? I have a Norton 1K to use for this purpose.
My guess is that after the spine and the blade edge evens out, then the bevel is easily set on the DMT 8k and honed to shave ready on the same steel.
Headdoc

That's one way to approach it, I guess. But perhaps not the best way. It really depends on the unevenness pattern (if there is one), but you could try to hone with the unevenness, particularly if it's related to a smiling edge.

Is the marker wearing off in the middle and leaving the tip and heel? Or is it the opposite? Or is there no pattern at all?

James.

The wear pattern is similar. On one the marker is showing in the middle of the blade and on the tip area. On the other, the last 1 inch on one side is left showing.
headdoc

I never worry about even wear on the spine, as long as the razor is not warped. I've never seen a razor (yet) that has even, matching wear on both spine and edge. The only practical way to get that would be if the spine and edge are both perfectly straight and/or very parallel to each other.

I'd just use the spine as a honing guide and try to give all parts of the edge "equal hone time".

If you're trying to remove a smile or frown on purpose, as opposed to just honing up a smiling edge, there used to be a barber's manual that covered the raw basics. I can't seem to find the link for it now. PM me with your email if you want me to send it to you.

Try using an X pattern stroke if you are not already doing so.
From your description of the wear patterns it does not sound like a warped blade nor a blade with a distinct smile nor a distinct frown. It does sound like an uneven honing stroke. Pay close attention to you honing stroke.