If you are using old card readers that use 26 bit HID cards for access, then the answer is no. Your data is not secure and your access control cards can be cloned.
HID cards are super easy to clone as the technology is open source.
There are even instructions on the internet!
You need to be aware that the technology you are using is outdated. Not only can the cards be cloned and used for malicious purposes, the data on your system can be manipulated and changed. Your access control system may show an employee accessing a certain area which in fact may never have happened.
You can no longer trust the accuracy of your security systems.
