Two TBS6981 - jamming each other?

[richh]

I have sucessfuly installed two TBS6981 under 2.6.35 into one system, so completely can recieve 4 transponders simultaneously.
Each of them working reliably without loosing signal. Immediately after starts recieving stream on second card both of them will starts to report that is loosing lock.
This loosage is not firmed - sometimes is loosing signal each 30s, sometime longer time. I have to note that I can realey recive and stream all 4 TS but when running from two cards it is disturbing signal to unusable.

Symptom:
When run
dvblast -a 0 -n 0 ... &
dvblast -a 1 -n 0 ... &
OR
dvblast -a 2 -n 0 ... &
dvblast -a 3 -n 0 ... &

No problem, stable stream, solid signal.

if run in same config from first reciever on 1. card + first reciever on 2. card
dvblast -a 0 -n 0 ... &
dvblast -a 2 -n 0 ... &
after few seconds loosing both cards lock

Where -a 0, -a 1 are frontends on first physical card and -a 2, -a 3 is second card.

Antenna is connected into passive 1:4 splitter. Frequencies of transponders are selected to be both in same polarization - mean to avoid some voltage fights for LNB on ports. I have to note that issue is same wheen I ask all stream to be recieved from same transponder. On one physical card I can start both frontend without loosing signal.

Board is ASUS M4N68TM V2, two PCI-E slots, one is 16x, second is 1x

Issue looks like to be fighting modules tbs6981fe (1.95) or they are not prepared/programmed for multiple those cards in one system. My hypothesys is that module disinterpret some (I2C ?) communication as disconnection and tell receiver to re-tune transponder.

I tryied varoius setup kernel to track issue on PCIe or I2C but nowhere is reported any problem.

Well there is still some possibility that one card is able to jamm second card reciever through splitter, but because somewhere else was declared that all recievers in fact independent even they are working on same board I guess there should not be change if using recivers which are on different boards.
I have to note that also power connector for 12V was connected, without any additional effect. Voltage for LNB also checked, not in conflict.

Any hint what to verify welcomed.