The Statsig SDKs use deterministic hashing to bucket users. This means that the same user being evaluated for the same experiment will be bucketed identically - no matter where that happens. Every experiment has it's own unique salt, so that each experiment's assignment is random.
For advanced use cases - e.g. a series of related experiments that needs to reuse the control and test buckets, we now expose the ability to copy and set the salts used for deterministic hashing. This is meant to be used with care. and is only available to Project Administrators. It is available in the Overflow (...) menu in Experiments.