Don't delete the KDE stuff since it will upset PCLOS.
so is the KDE message appearing when you login to mint?
I installed E17 last night on one of my systems so now i have gnome and E17 as DTE's. when I chose E17 for the session login it asked me if I wanted to make it my default desktop (this is normal), i chose "for this session only".
are you getting that kind of message?
if it is there is most likely a default session file in your home directory about which session is your default, it may also have which session you used last login.
going between PCLOS and mint may change the values in this file each time you login to each one.