Is it permissible to wipe over the outer sock if the one underneath it is below the ankles?

There is no harm in wiping over the upper khuff (leather sock) if the feet are covered and both khuffayn (plural of khuff) were put on while in a state of ritual purity. So, whoever performs ablution and puts on a khuff, then puts on another khuff over it before nullifying their ablution, they may wipe over the second khuff.