Thanks for the information, I just made the test via Postman with the function get_ops_in_block and all the transactions of the block 41868606 are duplicated in the answer

{
    "jsonrpc":"2.0", 
    "method":"account_history_api.get_ops_in_block", 
    "params":{"block_num":41868606,"only_virtual":false}, 
    "id":1
}

So after some cross-checking I went back up to block 41868590 to finally have a block where the transactions inside are not duplicated. In the other direction, I had to get to block 41868612 for it to finally stop.