Yes, it is possible to do this and infinitely many other combinations

What I would do is
(1) start with the Mapped Key Wizard (in the Wizards menu), and
(2) select the "Straight Key Broadcast Plus Click" style of Mapped Key. This will help you set up one or more Mapped Keys of this particular style, which will send the key you press to any given window, and also initiate Mouse Broadcasting until you click in order to aim the AOE!
(3) Set it up to send your AOE spell to the guy that needs the AOE, and then
(4) AFTER finishing the wizard you can go back into your new Mapped Key, and
(5) add in a Keystroke Action to do your "normal spell" on the other guy.
(6) And change (or remove) the Hotkey if you want since you wanted to do this with a Click Bar. That's it!
You might need help with that last part, so I'll detail how to add in the different Keystroke Action:
1. In the top left pane under Key Maps, select the same Key Map you added your new Mapped Key to
2. In the bottom left pane under Mapped Keys, expand your new Mapped Key so that under it you see Steps, 1
3. Select the 1 under Steps
4. In the bottom right pane under Step, Actions, right click Actions and, under Keystroke Actions, select New Keystroke Action
5. Set the Key Combination to whatever the "normal" spell is
6. Set the Target to whoever needs to press that key
And of course if you want to adjust the Hotkey to activate the Mapped Key, select the Mapped Key in question in the bottom left pane and the Hotkey option is at the top of the bottom right pane.