question on disenchaning duplicates of the gifted temp cards

Sorry that I'm one of the many asking these questions but I opened my new xpac packs and as usual I was going to disenchant my duplicates and then it mentioned disenchanting the old xpac doubles that I now have extra of because of the temporary loan expansions like the emerald dream ones. I figured it would just DE the new cards but I don't want to accidentally get rid of the old xpac cards and then lose them when the temps go away, they shouldn't be a part of the mass disenchant really. Am I going to have to go card by card now to avoid this? Did that make sense?