When you install task-lxde the trash icon gets put on the desktop. It's completely useless. You can safely delete the lxde trash icon. But check to be sure it is the lxde trash icon - in pcmanfm > /home/<you>/Desktop > right click the icon > open with - and have a look at its .desktop file.
If you need a trash function in lxde, install xfe (x file explorer). It has a good trash function and is relatively small. I've been using it for a long time now - on those rare occasions when I need a trash function.