Hey thanks.
Out of curiosity, do nodes selectively sometimes avoid "double spend" transactions out of safety concern, or they don't care. I've receive 2 confirmations after 1 block so I am wondering if that's because some nodes choose not to take it because of the double spend broadcast. Or it could just be the traffic or low fees
nodes can modify their settings to accept or reject anything they want.
what they should do is that they should reject any transaction that is a double spend.
but what you did is probably an RBF transaction. those things are like an exception. in your first transaction you tell everyone that you may change this transaction to increase its fee (replaceable by fee), so nodes expect it to happen. those nodes that allow RBF transactions won't reject this kind of double spend and simply replace it with the new one.
Thanks, that's a very good explanation.
Though wondering if RBF might end up being a bad samaritan, since users might start with low fees and rebroadcast again chocking up traffic.