we would normally only ask for that if we were taking you over a sage 200 customer.  i believe permission has to be given by you for Sage to talk to a new prospective Support company, and the account and serial number will then provide them with the information of what licences modules etc you have,  this will then let them work out by their own formula how much to quote for support.  i believe we go through when we are asked to quote.  there is no danger in giving the information and permission,  until YOU tell sage that you are switching then you will still be supported by the original provider.

So in short, yes it probably is normal, there is also no danger, and no changes made, unless you tell that you are going to use the new supplier,

As Toby says. It is normal if you are changing Sage Business Partners, for the new business partner to ask your permission to talk to Sage regarding you Sage installation. However, it is unusual for an IT company to ask for this.