I dont have experience with WORM tapes, but from what I read, you can write to it multiple times. However, a LTO-3 or later drive will not erase or overwrite data on a WORM cartridge, but will read it.
As I understand it, there is nothing different about the tape medium in a WORM cartridge. So, older tape drives, not supporting WORM, will be able to read and write to them repeatedly.