What brand of HD PVR2 is it? If it is the 2P, then possibly a small change to the network settings will sort it out.
The issue is you are getting a clash between the user bands and frequencies used by the two decoders.
The 2 tuner decoder uses userbands 0 and 1 as default and therefore either this has to be changed to user band 4 or 5 if it is a 2P, OR
You must change the Explora to use userbands from 2 onwards to fix.
Easyview, UEC 4T HD PVR, SD PVR, XV
Spare decoders: SD PVR(2), PACE HD PVR 4T, DSD 660, 1110, 1131, Explora
2 unmentionable FTA decoders
Win 10 Pro (64-bit) build 1607, version 14393.351
1.2m antenna, 8-way universal LNB, 2x6 MS, FSM permanently connected.