Both transactions won't go through; miners will only include the one with the higher gas price. The other will be marked as "Dropped & Replaced". Because the nonce for a single address is sequential, miners can only accept one of them.
1. What Is a Nonce Anyway?
Nonce is a transaction counter that Ethereum assigns to each address. The first transaction has a nonce of 0, and each subsequent transaction adds 1.
Miners follow two strict rules when processing transactions:
Strictly sequential nonce order: If the transaction with nonce 0 hasn't been confirmed, transactions with nonce 1, 2, etc., must wait, even if they offer higher gas.
Nonce cannot be skipped: You cannot jump from nonce 0 to nonce 2. If nonce 1 is missing, nonce 2 will never be mined.
2. Two Transactions with the Same Nonce: Which One Does the Miner Choose?
When two transactions share the same nonce, the rule is straightforward:
Miners will only accept the transaction with the higher gas price. The other one is discarded from the mempool and shows the status "Dropped & Replaced".
Etherscan officially defines "Dropped & Replaced" as: a transaction that is dropped after a new transaction from the same address, using the same nonce and a higher gas price, replaces and confirms it on the network.
This is actually the underlying mechanism wallets use to "speed up" or "cancel" a transaction:
Speed up a transaction: Send a new transaction with the same nonce but a higher gas price to overwrite the original.
Cancel a transaction: Send a new transaction with the same nonce, higher gas price, but with a value of 0 and to your own address, effectively "withdrawing" the pending transaction.
3. Why Would You Send Two Transactions with the Same Nonce?
There are three common reasons:
Reason 1: The transaction is stuck, so you manually speed it up or cancel it
The original transaction remained unconfirmed due to low gas. Your wallet helped you resend a transaction with a higher gas fee. Now you'll see the original marked as "Dropped & Replaced" on Etherscan, while the new one confirms normally.
Reason 2: Wallet or node is out of sync, causing a wrong nonce count
Two wallets are operating the same address simultaneously, or a connected full node is slow to sync, resulting in the same nonce being used.
Reason 3: You accidentally sent two transactions
A manual mistake: you sent two transactions with different content but the same nonce.
4. After One Transaction Succeeds, What Happens to the Other's Gas Fee and Amount?
The replaced transaction never goes on-chain, so:
No gas fee is deducted for that transaction
The transfer amount doesn't change
Your account balance reflects only the effect of the confirmed transaction
Risk warning: If two transactions with the same nonce are broadcast with similar gas prices, during network congestion miners may have different judgments about which to include, making the final outcome uncertain. If the receiver and amount differ between the two transactions, you cannot fully control which one will be confirmed—it depends solely on which node's transaction gets mined first.
After making these judgments, how do you confirm which one ultimately succeeded?
Go to Eth erscan, enter your wallet address, and find the nonce in question in the transaction list. The one with the status "Success" is the one that got confirmed on-chain; the other will show "Dropped & Replaced". If both show "Success," they aren't the same nonce at all—double-check the nonce number you copied.
