Why the phone MAC bytes keep changing?

I'm using an nRF52DK to monitor the RSSI and MAC address of my two phones through ble_evt_handler BLE_GAP_EVT_SCAN_REQ_REPORT.

I tested both Android and iPhone. They both showed strange behaviors regarding the Bluetooth address.

The iPhone changed its own address to a totally different one at each session.

The Android phone keeps its own address but the LSB byte keeps changing the value at each scan as follows:

<info> app: RSSI: -49
<info> app: C5 F3 85 AC 00 CF
<info> app: RSSI: -38
<info> app: C5 F3 85 AC 00 DA
<info> app: RSSI: -40
<info> app: C5 F3 85 AC 00 D8
<info> app: RSSI: -50
<info> app: C5 F3 85 AC 00 CE
<info> app: RSSI: -45
<info> app: C5 F3 85 AC 00 D3
<info> app: RSSI: -41
<info> app: C5 F3 85 AC 00 D7
<info> app: RSSI: -45
<info> app: C5 F3 85 AC 00 D3

If we pair the phone and the nRF52DK, do they 'remember' each other address? How does that work if the addresses are changed?

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