This is the last entry for the book of Numbers. This contradiction continues the previous entries on the Torah’s variant asylum traditions (see Contradictions #345, #346, #347) and seems to be created by a spurious verse embedded in the Joshua passage.
That is both the Priestly passage of Numbers 35 and the Priestly redactional work of Joshua 20 state that the murderer who murders another by mistake must remain in the city of refuge until the high priest in Jerusalem dies. But Joshua 20:6 also suggests, erroneously it would seem, that he must remain in the city of refuge until his trial.
He shall live in that city until he stands trial before the congregation for judgment, until the death of the high priest who is in office at that time.
Most translations add an “and” before the second until; but it seems apparent that the verse went through some editorial mishandling. It’s quite possible given what we looked at in the previous entry (Contradiction #347) that the phrase “stand trial before the congregation for judgment” might have originally belonged to the judicial procedures required prior to gaining admittance to the city of refuge. At any case, Joshua 20:6 exhibits two contradictory conditions describing when the manslayer is allowed to leave his city of refuge.