Is it permissible to wipe over two socks worn one over the other, and if it is permissible and he wipes, then takes off the first sock, and his ablution becomes void, is it then permissible for him to wipe after that?

It is permissible to wipe over the outer khuff (leather slipper) or sock if it was worn after hadath (a state of ritual impurity requiring ablution). If the outer one is removed after wiping over it and the wudu' (ablution) becomes invalid, it is permissible to wipe over the inner one, according to some scholars.

Sheikh Ibn 'Uthaymeen summarized three cases: 1. If the outer khuff or sock was worn before wudu' after hadath, then wiping should be performed on the first one (the inner one). 2. If the outer one was worn after wiping over the inner one after hadath, it is permissible to wipe over the outer one according to the correct view, and the period of wiping is calculated from the time of wiping the first one. 3. If the outer one was worn and wiped over, then removed, is it permissible to wipe over the inner one for the remainder of the period? This was not explicitly stated, but Al-Nawawi argued that the jurmooq (a khuff over a khuff) and the basic khuff are considered as a single khuff, with the outer one being the exterior and the inner one the lining. Based on this, it is permissible to wipe over the inner one until the end of the period for wiping over the outer one.