"In stand-alone mode, rippled does not communicate to other members of the peer-to-peer network or participate in a consensus process. Since there is no consensus process in this mode, you must manually advance the ledger index using the ledger_accept method"" - https://xrpl.org/advance-the-ledger-in-stand-alone-mode.html
This might influence whether transactions are actually stored on the ledger before sending another request from the same individual.
"In stand-alone mode, rippled does not communicate to other members of the peer-to-peer network or participate in a consensus process. Since there is no consensus process in this mode, you must manually advance the ledger index using the ledger_accept method"" - https://xrpl.org/advance-the-ledger-in-stand-alone-mode.html
This might influence whether transactions are actually stored on the ledger before sending another request from the same individual.