multiple entries for roles in the old database are split to separate roles in the new database

The following serves as an example:
entry in old database

parameter_pi: "Christian Ohlwein, Jan Keller"  
parameter_pi_email: "ohlwein@uni-bonn.de,jkeller@uni-bonn.de"  

should be converted to two entries in the new database (example for table persons, which entries will then be inserted into contacts and will then be used for the different roles:

id: 
name: "Christian Ohlwein"
email: "ohlwein@uni-bonn.de"
phone	""

and

id:
name: "Jan Keller"
email: "jkeller@uni-bonn.de"
phone: ""