How about telling us the addresses in question, or even better, the supposed TXID's?
The point of sending a second transaction is because that second transaction would get higher priority, as it has a higher fee.
Let's call them Transaction A and B, you didn't have a fee on A, so you send the exact same transaction again, with a fee, and that became B
Because B has a higher transaction fee, it has a higher chance of getting confirmed. Assuming both transactions are equivalent, it shouldn't matter which one confirms, as only one should confirm assuming the inputs (think of them like coins) are the same. When one confirms, it cancels out the previous one because the previous one would become a double spend, thus become invalid.
When that happens, you may get the original transactions coins back. You may need to start Bitcoin with -rescan (google it) before it will detect that transaction is now invalid.
here is a link to the transactions on the address:
https://blockchain.info/address/1MFx5s4ehcSKYGD8fEAHvapewMiXJMFeKFThe first transaction of 0.0003 btc is not being confirmed and there is another for 0.05 btc (paid a small fee of 2.26 ubtc) made around the same time and is not even being shown.
So according to how this double spend works are you saying I cannot make the exact same payment amount twice to the same address if done around the same time? By the way I already did the rescan but didn't do that double spend thing yet.
The transaction will disappear from your wallet and the amount will be added back. However, I would advise you to spend it after waiting for sometime since most nodes would not have forgotten about the transaction and they would not transactions spending same inputs.
sorry but I'm a bit of a noob and didn't get the bold part. What happens if I don't spend it within any specific time frame?