Multiple MAC addresses on same RS1D

Hi RSH.RAF16.2019-11-25T16_09_50.logs.tar (2.1 MB)
I am trying to set up a RS1D with a pizeroW (for use in battery powered situations) when i first configure the RS1D I use a usb-ethernet cable with direct connection to DCHP hub. I have then confiugured the wifi to access the internet via mobile wifi hotspot.

This has resulted in teh device having two MAC adresses (one associated with the wifi and one asssociated with the USB-ethernet adaptor) .
How is this handled within the rshake ?
what do I need to do when i swap over from USB-ethernet to wifi (hard reset ? soft reset ? disable uploads ?)
or should i avoid using teh USB-ethernet adaptor entirely and aim to confiugure the wifi at teh initial boot stage (can i do this by editing a file on teh sd card before i boot ?)

thanks

paul denton