Telephone assessment by two different providers in two days?

My friend had a PIP telephone assessment on Tuesday (yesterday) with a provider she thinks is called 'IS' she told them she had an appointment for a call today! The assessment went ahead, she was advised to tell the other provider that she did not need to carry out a second assessment and that her claim is now in progress. Today the other provider phoned and requested they change her interview time to tomorrow morning, she told them she had already had her assessment and did not need to have the call. They have told her she still needs to take the second assessment. Will this be because the second company won't get paid ? She is recovering from a serious brain trauma and getting really worried and fretful about this. Surely she shouldn't have to have two assessments within two days. Any help would be gratefully received. Thank you