When sending out the funds from the wallet to the same address with the second transaction too close to the first one, you may see an error message saying “Previous transaction is still pending. Wait for it to be processed”.
This occurs when the first transaction hadn’t been signed and sent to the mempool by the time the following request for withdrawal of funds was made. In this case the system interprets consequent transaction as double spending and tries to block it.
Wait for the status to change to Sent and try again later.