I've been setting up a couple of computers with Ubuntu, and making sure they all have a couple of packages I need. When I looked for the packages in the software centre on most of them they were there, but on a couple they were nowhere to be found. I got them just fine using apt-get, but it seemed odd that the selection in the software centre was inconsistent between otherwise identical computers.
Next images maybe will give you an idea:
So, the software sources must to be the same on all computers about that you speak if you want to find the same things everywhere in those computers in Ubuntu Software Centre.
To open and select software source, search for Software & Updates in Dash.
Also, for troubleshooting, a good general procedure not only for Ubuntu Software Centre is to run next set of commands from terminal:
sudo apt-get clean sudo apt-get update sudo apt-get upgrade sudo dpkg --configure -a sudo apt-get install -f