Validate current assumption of ledger behavior

**Description**

PR #501 assumes -- as experiments with fabric seemed surprisingly to have shown .. -- that fabric always returns only the commit value, even if the chaincode in the current transaction has issued a `putState`. On the other hand, fpc currently allows multiple `putState`s (with the last one counting). As fabric behaviour seems a bit surprising and we might have missed some other subtleties which could lead to behavior which is unexpected to chaincode developer (and potentially insecure) we should cross-check with fabric maintainers ...

**Link to feature or bug**

**Link to dependent issues**