Commentary for Oholot 8:6

בשני חצאי זיתים – half an olive’s bulk in this one, and half in that one.

Two [earthenware] jars in which there are two pieces of corpse the size of half an olive, sealed with tightly fitting lids, lying in a house, they remain clean, but the house becomes unclean. I bet you read this situation and said to yourself, yes, that's happened to me. Two tightly sealed jars, with two pieces of corpse less than the size of an olive in each, sure, common situation ☺. In all seriousness, the tightly sealed jar does not prevent impurity from coming out in an ohel. Since between the two jars there is the necessary olive's worth of corpse, the house is unclean. However, each jar remains clean because a tightly sealed lid prevents impurity from defiling an earthenware jar.

הבית טמא – that a tightly-fitting cover does not protect on the defilement that is under it so that the house would defile the house, but even though that they are in two jars, for since both of them are in the house they combine to the measurement to defile the house. But the jars are ritually pure, for the defilement of one-half an olive’s bulk that is in its companion jar enters into it, sine it is surrounded with a tight-fitting cover.

If one of them was opened, that [jar] and the house become unclean, but the other remains clean. If one jar was opened, that jar is unclean by virtue of being in the house. However, the other jar remains pure. The house is unclean as it was in section one.

וכן שני חדרים שהן פתוחים לבית – and their doors are locked, and there is a half-olive’s bulk in this room and a half-olive’s bulk in that room, the house is impure, for ultimately the defilement exits, but the rooms are ritually pure, for there is no pay for the defilement to enter in.

A similarly with to two rooms that open into a house. If there is half of an olive's worth of corpse in each room, and the doors to the house are both locked, they join together to defile the house, because eventually these pieces of corpse will be brought out through the house. However, the rooms themselves remain pure because there is less than an olive's worth in each.