yes, PlayMakerUnity2d script isn't necessary anymore if you have the latest version of PlayMaker.
I would suggest the following:
1: backup your project
2: get the latest version of PlayMaker
3: during installation, check the updater, it shoudl prompt you with what's not included officialy within PlayMaker. clean up your project so that the updater finds nothing potentially clashing and you'll be good.
Let me know if you struggle with this.