You probably used the Ctrl key with your mouse and did not remove your
finger from your mouse after selecting a photo, instead you dragged the file
name downward and this started to make copies.
Select the first picture with your mouse, remove your finger from it. Hold
the Ctrl key down, click with your mouse on the next picture. Remove your
finger from your mouse etc. When done, press Delete.
To delete the 360.
Click on the first one with you mouse, remove your finger from the mouse.
Hold the Shift key down, click on the last picture. Release the Shift key,
remove your finger from your mouse. Press Delete. Don't forget, all these
deleted files will go to the Recycle bin. Open it and delete them out of
there.