No and No.
You cannot connect an equalizer to two receivers of any type simultaneously. It nmay work but I can think of several problems that could possibly cause it to fail.
Most, actually all, DD/DTD digitally based AV recevers*, that I've seen cannot accept an equalizer because they lack a true "tape monitor" circuit which break the circuit, sends the signal out to the eq, and then right back into the receiver where it left.
Plus, consumer eq's only handle two channels. AVR's have five or more channels.
DPL, or Dolby Pro Locic, based receivers are a different animal and may allow it. They are matrixed, not discrete, systems which work off an analog two channel signal.