Sometimes you can find, that in your main menu the same application is represented two times. In my case I've found a "Dictionary" application two times. It looks like this:

First thing: why did it happen? The answer for this question is very simple: if you try different desktop environments (for example: IceWM, XFCE, KDE etc), each of them installs its own set of applications. In my case I tried XFCE and GNOME and every time desktop environment installed the same application. How can we know about it? Just click on (in my case: "Dictionary") application with right mouse button and choose "Edit application":

You see: the same application, the same shortcut in Main menu, but in fact: two different applications:

• xfce4-dict
• gnome-dictionary

Now: small portion of theory: Those two names "Dictionary" are not applications, but shortcuts, which launch real applications installed in your system. In fact, in Main menu you see something like LINKS to real applications. In my case those two shortcuts have the same name ("Dictionary"), but they launches two applications.

What to do?

It is surely up to you, what to do. The thing is, that you don't need the same application in your system twice. So, you can delete both of them through application/software manager (in my case: YaST), or leave just one. I will try to delete them both, because I really have no need in it.

Deleting

So, let's go to YaST, type "Dictionary" in search tab  and check, what we have here:

Now we see, that yes, it's true: two applications: 1) xfce4-dict and 2) gnome-dictionary are installed in my system.

Let's uninstall them by clicking the white checkbox before the name of the program:

Then click "Accept" in right bottom corner of the window and uninstall dictionaries.