I am using a strategy where for example the second position I open is double the first position (is just an example)....
I have tried different cryptocurrency exchanges but they open my order with a different amount than the one I had chosen...
do you guys know any cryptocurrency exchange that opens my orders exactly with the amount I choose?
I am not sure I get what you mean...
Do you have any screenshots? Maybe that would help me understand better what you are talking about?
Are you using limit orders or stop orders?
Didn't understand OP too, from the first glance at it - it looks like he wants to open the first position and then the second one with the same amount of funds for it - but simultaneously.