I occasionally come across double-leaf fire doors with smoke seals on both sides of the meeting stiles.  Is this a valid configuration?   To be effective, a smoke seal should surely be making contact with a solid surface rather than an opposing seal.

A further consequence of such configurations is that the overall meeting stile gap tends to be greater than that of doorsets where just a single smoke seal exists.

Thanks in advance for any guidance!

Seals should be fitted to the main leaf only so as not to be interrupted by flush bolts at the top and bottom edge of the secondary leaf.  Where there is no bolt the seals may be fitted to the meeting edges of both leaves but offset, not opposing.