ok follow this

remove all the torrents u downloading from dc at the moment

login to ur account on dc and go to usercp

from there reset your passkey

then change your password.

now download torrents from dc again.

your torrent will show new passkey. copy passkey and paste in notepad

then download another torrent and check passkey in it and compare with the one u pasted.

if they same everything fine.

i think someone might have got access to your account. follow these simple troubleshooting steps and if problem persists then we will try helping u out as to how to tackle with caching problem.