I am looking for a way to mount two small pictures side by side (perhaps, say 3" x 5" where 5" is vertical), and then a small brass engraved tag underneath.

Something like the attached.

The most common way is to use 3" x 5" Plexiglas to cover each photo and screw them to the plaque. Another option is to use "clear top load" plastic type pouches and use 2-way tape to attach to the plaque.
Plastic Plus has these listed on page 121 of the 2007 catalog but come in 3" x 4" or 4" x 6", not 3" x 5".

Does this help???

~

Ed,

I use that type of template for a lot of my perpetual plaques as well.
Use a piece of Rowmark plastic, using CorelDRAW for alignment, cut out a space for each plate, tape the template to the plaque, position each plate in the appropriate space, drill holes or tape plate down----DONE!
No more mis-aligned plaques and 10 times quicker than manually placing & aligning.
;-)