Switched from EE and now appear to have 2 lines with the same number.

I switched from EE last week using a PAC code. It all seemed to go ok but I could see both my number and the new ID number on my phone labelled primary (EE) and personal (ID). 
I realised tonight that I couldn’t make calls. I’ve switched the phone off and on again and now both personal and primary have the same number, the correct number that I transported. I’ve set the personal (ID) line as default and now I can call out but I just wondered if I have done something wrong? And if it will cause me problems having my phone set up like this? 
when I call someone I’ve previously called it says I cannot use the same line and would I like to use the alternative line!