Doorbell detecting person

I have a "basic" battery video doorbell. My wife left the house, cross over the road to the house directly opposite, put a card through their door, and returned immediately back to ours.When she left our house it picked up "person detected" and recorded for around 15 seconds, but when she returned back I have a "basic" battery video doorbell.My wife left the house to cross the road to put a card through the door of the house opposite, and immediately returned back.Our bell picked up "person detected" when she left our house, and recorded for around 15 seconds, but when she got back (after the 15 seconds) it did not repeat "person detected"Is there a built in delay after the first detection before it can detect again?Hope someone can advise me, thank you.Steve