Map cards purchased from Tomtom are locked to the SD card and can be transferred to other Tomtom models. Stick the card in the 710, and follow the steps here to install the 710 application onto the exising map card.
Maps downloaded from HOME are locked to the Tomtom's device's serial number and therefore cannot be moved to another device.
I'm not sure If the map card was originally included in the Tomtom ONE box is SD-locked or device-locked. What you can do is attempt to copy it to another SD card and put it in your ONE. If the map works, then it's device-locked and won't work in the 710. If the map doesn't work on the SD copy, then it's SD locked and will work on the 710.
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