Why bitcoin cash supply is currently 100k more than bitcoin on coinmarketcap (as of Oct 17) Is it a mistake or is there a significant difference in coins generated?
EDA (Emergency Difficulty Adjustment):


  Median Time Past of the current block and the Median Time Past of 6 blocks before has to be greater than 12 hours.
  If so, it gets 20% easier to create proof of work. In other words, miners can find blocks 20% easier.


Source: Jimmy Song

As EDA is one way (difficulty down), miners abuse it. They stop mining, and after the EDA comes, they start mining with a big hash power. This is the cause of Bitcoin Cash's hyperinflation: ~7500 blocks ahead of BTC and 7500*10/60=1250 hours of blocks ahead.

The developers are aware of this issue, and it'll be replaced on 13th of November, by a newer difficulty algorithm.

They haven't decided which algorithm to switch, but probably it'll be Dgenr8's. [1][2]

1: https://www.yours.org/content/dgenr8-s-difficulty-adjustment-algorithm-explained-01a2de286460/

2: https://reviews.bitcoinabc.org/D622