how implement two inputs for node ?
node-red version 3.1.1
I believe this has been raised many (MANY) times before.
A possible solution is to make input 1 and input 2 messages have a different attribute.
eg: msg.indentifier == 1 and msg.identifier == 2 for the two different messages.
Then parse the message structure to determine who sent it.
Also understand that nodes only accept ONE MESSAGE AT A TIME, so two inputs wouldn't really work.
And - back to what I was saying - you WILL HAVE TO store one of the messages in context so when the second one arrives, it has the other one.
Other thought!
Use a join node to receive two messages before onsending it.
Then BOTH messages arrive at the same time.
But that may not work if there is/are overlaps in the message structures.
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if you create a custom node with two inputs, it still won't work ? is it limited in the node-red source code itself ?
No a node with two inputs won't work.
Node-red is not synchronous.
Messages arrive at unknown times.
So there will be a problem that one message arrives and it (your node) then has to wait for the second message to arrive.
I offered two ways around that.
I shall say though:
I am still very much in/at the shallow end of knowledge.
Node-RED makes the hard limit of zero or one input to a node - there is no such thing as a 2 input node.
It's an inbuilt assumption.
For reference, just a small selection, where this has been discussed: 
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