One Extension Cord into Two Outlets

I want to plug my exhaust fan into a cycle timer and also plug it into my sentinel thermostat. The reason I want both is that the thermostat is set to turn on my exhaust at 79, but it almost never reaches that temperature (though it does occasionally). And if I lower the trigger temperature, the fan takes forever to shutoff or is repeatedly turned on and off.

So I am looking for a cable that would allow me to have my exhaust fan plugged into both a cycle timer and my sentinel thermostat at the same time.

Does one exist?

You mean something like this?
http://www.unbeatablesale.com/peppp19709.html

no, i think i need two 120 volt relays.

want to run cO2 so bad but this is also going to be my delima....I know it will be without even trying.......what you and I both need is basically pluggin one item(exhaust fan) into two power sources....that way our fan doesnt kick on when dose cO2....but still have the fan kick on when temps climb....I think we can achieve this through using relays....or stepping up to a kick ass greenhouse controller(expensive)....IDK....if you figure it out don't forget about me.

endlscycle: exactly.