why many malwares have the same name?

Viruses and worms
1

these are infected files on my computer, why do they have the same name?
???
Images.exe
setup.exe
updater.exe
userinit.exe

→ Win32:Trojan-gen {Other}

2

Do you mean the same virus name?
Well, virus usually use the randomically change of the file names trying to bypass common user protections.

3

If you mean Trojan-gen, that’s just that nobody bothers to name the stuff, because it’s usually so short lived, so it does not have any sense.

4

:o I don’t know why my computer always infected with Win32:trojan-gen {other} ;D
Do you mean they are not very harmful?
what dose the word “other”(after the virus’ name) allude to?

5

That’s just you’re “lucky” to get somewhere where you get infected. Don’t know how it’s possible that avast allows the stuff to be dropped on your disk (except that you turn avast off for a while).

{other} just now means nothing, in the past there were different kinds of strings, right now it could be safely omitted, but I chose not to.