Why were the ingots mostly round?

[Jeff Pringle]

If the big ingots were so difficult to make, why did they not make the small ones only?

Taken as an entire process, I don't think there is a huge difference in difficulty between big and small ingots, and there are considerations such as efficiency of the furnace, and success rate of the final product.
Plus, as anyone who is making the stuff can tell you, many of the 'two-sword' ingots get to be 'one sword'- or 'several knife'-sized by the end of the forging process - if you only made ingots big enough for a sword, you'd end up with a lot of knives, and maybe not enough swords!

Is it possible to forge left over from two different ingots together and get a good result?

They did it back in the day, I don't know if anyone has gotten the technique down in modern times.

How close it the wooz pattern in the ingots made in the same furnace?

Very different, even within the same batch or ingot. I think Ric Furrer did a test of a Sri Lankan(?) type of crucible that was designed to be laid on it's side when the metal was molten, to give an oblong bar - IIRC, two ingots made of the same metal fired at the same time gave very different patterns in the final surface.
I find a fair degree of uniformity in patterns within an ingot, but each ingot varies in pattern depending mainly on carbon content and solidification rate.

Justin - this article explains the patterning in wootz steel -
http://www.tms.org/pubs/journals/JOM...even-9809.html