It's a pain that konqueror opens two panels by default in 'filemanagement' mode. I always have to close one by hand.

You can sort that in the profile:

/home/laussy/.kde/share/apps/konqueror/profiles/filemanagement

Forcing one view only:

ContainerT0_Children=View1

(you may have fun customizing the rest). This should address your problem of "konqueror opening with two windows" or "with two tabs" (these are the keywords I googled with no success). "Hi" if you found me this way ;)