I haven't encountered this exact problem but I have had LLMs make occasional transcription errors when "copying" hex strings around (e.g. cryptographic constants). They make surprisingly human-like mistakes e.g. a transposed pair of digits, which can be annoying to track down.

But this seems orthogonal to token usage, and if I was designing an "LLM-friendly UUID" it would have some additional checksum data, to detect transcription errors.