I chose the Delete original RAW file option
I do not know where you found this option!
(RAWs = proprietary camera originals NEF,CR2, etc)
Any time I run the Adobe DNG Converter I only have options to save the DNGs to the same folder, or specify a new folder. My 'Original' NEF raw files remain untouched in the folder containing the NEFs.
It requires a manual exercise to delete the original RAWs from the computer, and if you optioned to place the DNGs in the 'Same' folder as the RAWs, then you would need to sort the files with File Explorer to bulk delete the RAWs.
So I am not surprised that you "see double of my data".
You will need to delete the RAWs (and remove from Trash) to recover disk space, leaving the DNGs remaining.