Separate merged/welded vertices and create distance between them

Hi people,

I’m working for someone and I have to make low polys but their piece of s*** in house engine from the 1900s keeps crashing because it can’t handle floating vertices in the same place or welded vertices that share overlapping edges. Like this: composed for your viewing pleasure

so, as you can see I chose this approach for a fairly low poly as I’m making a church, and I successfully dropped it from 16k tris to 5k , but the cost is it not working…

Now I know the engine can handle floating geometry as it did before with no problems, it just doesn’t like it when vertices or edges overlap, but I don’t know the threshold of it’s taste.

So I’m thinking, How can I separate merged vertices (that I welded with “remove doubles” ) and after I separate them, how can I distance them let’s say 0.0010 units?

I’ve been searching google like crazy for the past 2 weeks, and no addon, no help has come up whatsoever!! >_<

Mesh / Vertices / Split to separate the selected vertices but do not create a new object from them
Mesh / Vertices / Separate to separate the selected vertices and create a new object from them