Yes. It is possible. But there are EAs which were designed to have one EA per MetaTrader, or one EA per chart. It does not depends on the Magic numbers only. Sometimes it is necessary to change something inside the code as well.

Recently we (together with Igorad) are trying to do some revision of almost all EAs posted on this forum to modify them to use in one copy of Metatrader (for example). This revision just started. It will not be changed anything inside the code except magic numbers (coding) and something about to avoid conflicting between EAs. It will be changed very small things which will not be affected on the trades at all. The new versions for testing will be posted as well. At first it will be posted in the our subscribtion section for discussion and late on it will be posted here.

Also Igorad is finishing the create some special script to generate the Statements. Because if you are testing several EAs using one copy of Metatrader you will want to get the Statements for each EA and each pair sorted by the time of open the orders (for example you want to have the detailed statements for all opennings from 8 till 18 for EURUSD only and for one EA only). So the second version of this script is issued already and we are still testing this script. It will be posted in subscribtion section first (for the discussion with the people who are professionally interesting in this subject and who are subscribers) and later will be here (of course).