It is possible to have more than one follower on the same tile using the magic portal as you've suggested, though not on the same feature.
However, if you are using the Count of Carcassonne, there can be several followers placed on the same feature (and I believe even on the same tile) after the feature is completed and before it is scored. For example: if three players have followers on the cathedral in the city, then when a cloister is finished, all of those followers can be moved to that cloister along with any meeple that may already be there. Unless, of course, the count in standing in the cathedral.
I hope you find this helpful. Welcome to the forum!