There exist several abilities that have the text similar to, this effect lasts while you maintain concentration (as if you were concentrating on a spell). One such example is the Bard College of Glamour: Mantle of Majesty ability.
At 6th level, you gain the ability to cloak yourself in a fey magic that makes others want to serve you. As a bonus action, you cast command, without expending a spell slot, and you take on an appearance of unearthly beauty for 1 minute or until your concentration ends (as if you were concentrating on a spell). During this time, you can cast command as a bonus action on each of your turns, without expending a spell slot.
Another example is the Cleric Trickery Domain: Channel Divinity: Invoke Duplicity ability.
Starting at 2nd level, you can use your Channel Divinity to create an illusory duplicate of yourself.
As an action, you create a perfect illusion of yourself that lasts for 1 minute, or until you lose your concentration (as if you were concentrating on a spell).
While you are concentrating on maintaining such an ability would you also be able to maintain concentration on a spell that requires concentration?
There does not seem to be any RAW that limits this however the limitation around concentrating on a second spell exists which may suggest that the intent is that a character cannot concentrate on 2 effects at the same time unless explicitly stated.
