Should legal documents generated in a staging environment have a watermark to avoid legal issues with testers?

Please let me know asap if this question is more suitable for softwareengineering or another design or legal exchange.

Context: I run the technology for a company that provides loans to students. We have contracts which are automatically generated, and we've built an in-house document signing system. We have several environments, including dev, staging and production. Most QA testing occurs in the staging environment.

Question: When generating contracts in the staging environment, should we add a watermark to say "illustrative", "example only" etc. or can we safely assume that since only employees use our staging site, it's more valuable to keep staging and production settings as similar as possible (for example, to avoid a situation where adding a watermark actually stops a bug occurring in staging that will then happen in live to real customers)?