I am replacing a Honeywell thermostat, model unknown, 8 wires w/ emergency heat pump with a programmable Honeywell thermostat, model RTH7400. The instructions for placement of the wires onto the new thermostat are conflicting, to say the least.

The following are the terminal codes on the old thermostat: R O B Y G C E W2. Honeywell's instructions are for attachment of old B to new C; however, new C already has the old C attached. The instructions state that if there already is a wire on new C, call a contractor!

Can any experienced person help me on this?

The instructions state that if there already is a wire on new C, call a contractor!

That would also be my recommendation also since there are a few different wiring configurations that could be possibilitys and if improperly wired damage to your system could result.