I think they have no idea about UTXO (unsent transaction outputs) imports. How they work and why to add them to circulating supply. The only compareable coin who did the same distibution is CLAMS (as far as i know) and if you look, the same issue with the circ. supply there.
I found something written by Jimmy Song the Editor of Bitcoin Tech Talk:
https://medium.com/@jimmysong/bitcoin-diamond-super-bitcoin-bitcore-what-you-need-to-know-f49c35688a39Bitcore is something that’s between a hard fork and an airdrop. BitCore (BTX) basically took the UTXO set from Bitcoin, compressed the outputs for each address and distributed on their chain. In layman’s terms, they cleaned up the ledger (blockchain) so that it’s a lot smaller.
This is the most clever of the hard forks in that it doesn’t require the Bitcoin blockchain like other hard forks do (120GB+!) and at least innovates by cleaning things up a little. Unfortunately, distribution on this coin is a bit stingier as you only get 0.5 BTX per 1 Bitcoin you had as of block 492820. They have a continuing airdrop going on, so there’s also that aspect which helps the coin.
The compare of hardfork and airdrop towards UTXO import shows me that this amount really should be added to circulating supply.
https://en.wikipedia.org/wiki/List_of_Bitcoin_forks