What you want to do will not work unless the two receivers are the same! I know this first hand as I had my HTPC HDMI out to a 1x2 HDMI splitter going to two Pioneer Elite VSX-01 and 21 receivers (very nearly the same thing.) This worked fine as the EDID information is similar and the HTPC saw them as the same thing. Fast forward and I switched out one of the Pioneers for a Denon. The problem is now that the EDID info is different and the HDMI splitter stores this info. So for example if the Pioneer was on first the splitter will see and store the pioneers EDID and the HTPC will see the Pioneer as a monitor. If you turn the pioneer off and then the Denon on the HTPC still sees the Pioneers EDID from he splitter and this does not work with the Denon and so I got a blank screen. The only solution is to power cycle the splitter which is not practical.
My recommendation and personal solution all though not the cheapest was to build a separate HTPC for my second zone. In the end it was worth the money spent to just have things work.