The problem lies in poclbm's support for X-Roll-NTime.
There are 2 patches for this applied to our source, first disable the header that allows X-Roll-Ntime.
And secondly disabling the support completely.

Seems to have fixed all issues we had.

jgarzik: The patch you merged that added support that, consisted of 2 commits for those two - we undid them.

Now - back to coding, our pool is growing extremely fast.
Sorry about the withhold of the solution. I'm all in for the sprit of the community, and all further patches will be publicly available at my own github.

We're _STILL_ having problems with low number of duplicates, but not even close to 5-6%.

Once again, sorry.
If you want to, donate the "bounty" to ius which works hard to help us out with both bugs and improvements.