Two SIM cards with the same number

Hi. My daughter's school has banned Smart phones. We have an old but working brick phone she can use. We don't want her to have a new phone number. There seem to be some providers that offer a second SIM with the same number. The second SIM doesn't need the internet. Does anyone know if SMARTY offer this? Or who else does in the UK? The other option is to swap over the SIM but the brick phone is a little fiddly to open and might break. Thank you 😊