@Techsolver74 When they are on the same SSID, they need a WIFI overlap to handover. If there is a gap in the WIFI signal, it will hold on to the distant access point. When you have different SSIDs, your device will see them as seperate networks and auto connect (a bit like going into the office and auto connecting to it).

@Techsolver74 

Exactly what Babbage said

Device are not that smart and your phone for example will hold onto the currently connected extender until it either loses signal from it completely, or you manually disable/enable and force it to reconnect

This is sadly the case in this type of setup

To force a device to move access points you have only really 3 options for you

1.  If possible, set the device to disconnect from an AP when the signal drops to a certain level.. say -70db.  This will force it to reconnect to the other "stronger" signal.  Being honest, most mobiles / tablets etc this is simply not possible

2.  turn the signal strengh down so the 2x dont overlap as much, that way it will force a reconnect

3. Invest in a Business grade APs and Controller.   Something like 2x EAP225s and a OC200 controller.  Then let the controller force the device to roam when required  (this is called 802.11K/V)