Re: Sending BTC to BCH or whatever coins, vice versa. Don't do this, newbies !
there is nothing to be surprised about. when you copy something you are copying everything including address formats. and that's just the tip of the iceberg because blockchair only has 2 of these altcoins otherwise you would have seen about 50 different addresses from 50 different copies of bitcoin.
Thank you for your reminder. Initially, I forgot to add that important information in OP. Now we have it. 
There are abundant coins with Bitcoin as prefix or suffix in their coin-names. Here is results from Coinmarketcap's Search tool.
