I currently have a Taco hot water recirculator in my house. I'd like to add a second timer to the system in parallel.

See picture below. Question, if timer1 is on, and then timer2 turns on at the same time, will this cause any problems electrically? The other condition is if timer1 is on, and timer2 is off, will the high voltage from timer1 hurt timer2 while it's off?