Many customers got this error using our APIs or with their own node. It happens if you try to broadcast a second transaction and the first one is still not mined, which means it doesn't allow you to create more than one transaction from same address in the same block.

Now this issue is solved and you can create as much as you want transactions from same address in the same block.

This is valid for Bitcoin, Litecoin, Bitcoin Cash, Dash and Doge.