Would I be able to place two different reads onto one chip? For example would I be able to use the XeM chip to unlock both my car door and a gun safe? Or does it only have enough space for one?
Yes and no. You can have only one ID on the chip but you can program that ID into multiple places. So as long as you can program a tag into both your car and the gun safe in the same mode, you will be fine. You will however run into issues if you need to run in different modes (HID vs EM) or if you need different IDs.
Thank you very much. Is there a device that I can get to tell me which mode it is?
Not really, you just need to know what device you’re using. If you are using the DT access controller it will be in EM mode. Otherwise you either need to read the manual of the product you have or ask the mfr.