It looks like Yahoo is making adjustments to their maladjusted prices.
This was a recent sample for XRX a few days ago:
[...]
Date Open High Low Close AdjClose Volume
20/06/17 28,73 28,88 28,31 28,33 28,09 2443700
19/06/17 28,72 28,99 28,54 28,79 28,54 3163700
16/06/17 27,88 28,84 27,84 28,50...