No you can't run one PC Owner started task for two(R19 and R20) different Datacollectors. You need one PC Owner for each release otherwise you'll get the following message when you try to start the Second Data Collector of a different release that the PC Owner Started Task:
DBG39050E DB2B 12:33:27 PC OWNER CODE LEVEL IS NOT CURRENT
DBG39042E DBGI 12:13:36 PC OWNER ALREADY STARTED
Also keep in mind that since R20 you don't need PC owners anymore. You could just keep your R19 PC Owner, and bring up all your R20 datacollectors with a new PCSSID and let them create the PC Owner environment themselves.