Yes this can be done. You can download the .deb file when you are at laptop 1, use the SSH file system (sshfs) to connect to your second laptop, then just copy from one to the other in Nautilus or whatever file browser you use. This can also be done if you installed the software on laptop 1 and the .deb is still in the cache folder (/var/cache/apt/archives). Just copy it from there to laptop 2 if you have ssh access to it, again using sshfs.
To use sshfs, it is similar to ssh in some regards. Switch -p for non-standard port numbers is just the same as ssh, otherwise the standard port 22 is used. Also, -C for compression over slow connections works.
Imagine Joe Bloggs has an account on both laptops. He has downloaded a .deb to laptop 1. He can copy it to laptop 2 using sshfs, then install this file when he gets home. Sitting at laptop 1 he has to do the following:
Make an empty folder in his home directory of laptop 1, perhaps called copies.
Type at the terminal: sshfs [-p oddportnumber] -C joebloggs@internetaddressoflaptop2: ~/copies
(Note the colon at the end of the laptop 2 address, and the space between that and the tilde.)
This mounts the home directory of joebloggs on laptop 2 inside the folder called copies on laptop 1 using ssh over the Internet.
Now copy the .deb file into the folder called "copies" in laptop 1 and it is actually copying via ssh to the home folder in laptop 2.
To unmount you have to type fusermount -u ~/copies
I hope this is what you were looking for.