Why cgminer keeps Rejecting

[kakakar]

Why cgminer keeps return lots of Rejected report, actually almost 95% are rejected. I'm playing with a Lancelot FPGA miner.
I tried combination of different version of cgminer and pools, but all the same result.
For example I used cgminer 3.1.0/3.1.1/2.10.x, pool btcguild, deepbit, even D7 pool.

Command line is like below:
cgminer -o stratum.d7.lt:8080 -u username -p password -S /dev/ttyUSB0

Cgminer Reject reports
 [2013-06-26 10:26:17] Accepted e69538a8 Diff 1/1 ICA 0
 [2013-06-26 10:26:17] Stratum from pool 0 requested work restart
 [2013-06-26 10:26:25] Rejected e69538a8 Diff 1/1 ICA 0  ((-2, u'Duplicate share', u"T
 [2013-06-26 10:26:33] Rejected e69538a8 Diff 1/1 ICA 0  ((-2, u'Duplicate share', u"T
 [2013-06-26 10:26:41] Rejected e69538a8 Diff 1/1 ICA 0  ((-2, u'Duplicate share', u"T

Anyone has an idea how to fix this?

Thanks!

[os2sam]

You can clearly see what is going on, your device, or CGMiner I suppose, is submitting the same share over and over again.  Now as to why? no idea.