Yes, you can purchase another identical RAM stick if available.
Yes, you can purchase another identical RAM stick if available.
There's not a 100% guarantee (even if you buy the exact same stick, they're still subject to change), but you will normally be fine. I very rarely purchase kits and haven't had an issue (yet). What speed are you running the stick at? I assume this is DDR5?
The RAM chip could vary in type. It might be from Samsung, Crucial, or Nanya. Intel CPUs tend to work well with a range of RAM options. AMD CPUs are quite selective about their RAM choices.