I just tested the simplest EA (No position -> Buy now, or https://fxdreema.com/shared/bq0ZqU1Fd) and it works as I expected. I put this EA on two different charts with the same magic, and I got two different trades.
Note that I'm using default settings for Group and Symbol, and I assume you are doing it too. And the default settings are such, so the trading blocks are working on the current symbol, and with magic number, equal to what the MagicStart parameter is.
There should be no conflicts between two EAs when both EAs are working on different symbols (like what I did above). In this case the magic number doesn't matter, because the symbols are different.
There should be no conflicts between two EAs when they work on the same symbol, but have different magic numbers. In this case because the symbol is the same, it's the magic number who prevents conflicts.