Why do I have copies of several log files?

[vr_anticipator]

I have copies of several log files as .gz file. I've been reading the logs for malware and scanned my pc with chkrootkit and I've found no signs of malware. But why do I have several copies of important log files? I am uploading pictures of /var/log/:

[ouroumov]

Those aren’t copies.
Logs are rotated.
Old logs are renamed with .N (number for ordering) and .gz (gunzip) because they are compressed so as to use less disk space.

[vr_anticipator]

Thanks. I am relatively new to Ubuntu. I am still learning. I clicked on a suspicious website yesterday, so I decided to see if I have received some type of malware. Plus, I wanted to learn how to read the log files in case malware ever happens.

Thanks for your time