What Are The Adverse Effects Of Having Over Dose Of Fentanyl Patch?

Hi, my Mom age 90 is on Fentanyl pain patch and has been for aboiut 8 years for Osteo and other back pain. She was due for patch change Tues March 10 yesterday. It was changed by her care worker.... then today a different care worker put a new patch on because she did not look at the calendar that shows what days the patch get changed. So that is two days in a row a new patch put on. This Friday March 13 is on the calendar for a patch change again. I am unsure whether she will have any affects like overdose if it gets changed again.