[Ethereum] error: replacement transaction underpriced – Nonce increment? how? Atomic transaction

trying to send 2 transactions through infura to ropsten smart contract, but got the error: "replacement transaction underpriced". For my understanding its a Nonce increment problem…tried this code without success…

var Contract = require('web3-eth-contract');
const contract = new web3.eth.Contract(abi, contractAddress);


web3.eth.getTransactionCount(account, (err, txCount) => {

    const txObject = {
      nonce:    web3.utils.toHex(txCount),
      gasLimit: web3.utils.toHex(800000), // Raise the gas limit to a much higher amount
      gasPrice: web3.utils.toHex(web3.utils.toWei('10', 'gwei')),
      //value: web3.utils.toHex(web3.utils.toWei('0.01', 'ether')),
      //value: 1000000000000000000,
      to: contractAddress,
      data: contract.methods.function1(["...).encodeABI()
    }
  
    const tx = new Tx(txObject, { chain: 'ropsten' })
    tx.sign(privateKey)
  
    const serializedTx = tx.serialize()
    const raw = '0x' + serializedTx.toString('hex')
  
    web3.eth.sendSignedTransaction(raw, (err, txHash) => {
      console.log('err:', err, 'txHash:', txHash)
      // Use this txHash to find the contract on Etherscan!
    })
})



web3.eth.getTransactionCount(account, (err, txCount2) => {

    const txObject2 = {
      nonce:    web3.utils.toHex(txCount2),
      gasLimit: web3.utils.toHex(800000), // Raise the gas limit to a much higher amount
      gasPrice: web3.utils.toHex(web3.utils.toWei('10', 'gwei')),
      //value: web3.utils.toHex(web3.utils.toWei('0.01', 'ether')),
      //value: 1000000000000000000,
      to: contractAddress,
      data: contract.methods.function2("....").encodeABI()
    }
  
    const tx2 = new Tx(txObject2, { chain: 'ropsten' })
    tx2.sign(privateKey)
  
    const serializedTx2 = tx2.serialize()
    const raw2 = '0x' + serializedTx2.toString('hex')
  
    web3.eth.sendSignedTransaction(raw2, (err, txHash2) => {
      console.log('err:', err, 'txHash:', txHash2)
      // Use this txHash to find the contract on Etherscan!
    })
})

Should I put in transaction2:

nonce = web3.eth.getTransactionCount(contractadress?) + 1 

or

web3.eth.getTransactionCount() + 0

I'm missing something, tried these options but I got other errors. These 2 transactions work when alone.
Are they possible to do in an atomic transaction, ie in the same block?