Yes, of course.
Let's say you are talking on a long call on your Leitner, and your buddy asks if he can charge his headset on your base. Well, now you can confidently say "Yes" and still remain on your call!
This can also work if you have super long shifts and have a spare headset. Charge one while one is being used, and by the time the first one goes down, the second one will be ready to go.
Bonus: If you do a permanent pair for training on the second headset, you can switch without anyone really noticing just by picking up the charging headset and turning it on!
Note: LH280/380 can only charge on another 280/380 base