TV's out of sync with each other

[AndyB11]

We often have two TVs on the same channel so we can hear from the kitchen.  One has a DVR and the other a STB (non-DVR).  There is a half-second delay at best and sometimes a 3-4 second delay with the DVR TV being behind the STB TV.  Hitting the FIOS button or turning the DVR off and on will reset the timing closer, but they are never in full sync.  Any way to sync the two to get rid of the echo effect?  Thanks!  Please note I have copied this questiion.  My question is there because of a need to know why? ?  ?  Why the delay?

[CRobGauth]

No way I know of to sync them up.

I believe delay is caused because of buffering differences between DVR and regular STB.