The data of EAs(Expert Advisers) and Custom/Technical Indicators will be only saved on your hard disk of your computer, but not on the trading servers.

Thus, if you are running an EA on one trading platform, you won’t see the EA installed from different platform even it is the same account you logged in.

In this case, all you can see is the trades made within the account.

So if you install the same Expert Adviser into two different MT5 platform but running for the same trading account, then your trading account will have two same trades placed for every order from your EA.

If you intend to do this, you are welcome to install the same EA to several trading platforms.

For more information about the use of MT4 and MT5 trading platforms, you may refer to educational materials available with the Forex Brokers.