Hi Miguel,
I have addressed this with FTMO support. They do not block traders until there is a total of all traders accounts adding up to $400,000. Once this amount is reached they will send emails to all traders trading the same strategy and ask them to change their strategy. It is only after they send out the email and the traders refuse to change their strategy that they will lock out your account. So, there is really nothing to worry about when trading with FTMO. Petko has started in another Topic you can change the strategy by changing the indicators settings by a small amount and it will not significantly change the performance of the EA. Petko also says you can change the strategy by changing the Magic Number.
Alan,