A-PDF TIFF Merge and Split is a program that can merge several TIFF images into just one.
It can also split a multipage TIFF into several single page files. This program is also able to convert from TIFF to JPEG, BMP, GIF, and PNG. The process will be made keeping the size and definition for every single picture. The resulting file size will be approximately the same that you will have by summing both files. You can add files for merging, or entire folders. You can have the names of the files to be added into a plain TXT file, the program can load them from that. Of course, you can also export a list using the program. The user can specify how will the resulting files will be named, the destination format and which quality should the program use to convert the selected files (only in JPEG and PNG files).
The demo version of A-PDF TIFF Merge and Split will let you merge just two TIFFs at a time, but it will extract all the images into a video file.
In brief, this program is a nice utility for people that often need to capture TIFF files from another sources.