[lwip-users] Duplicate sequence numbers

[JM]

I have yet another problem; I can't help but to think I have some type of compiler-related issue because of the seemingly unsolvable issues I'm having.  I just cannot get data flowing smoothly no matter what I do. 

I'm seeing "tcp_receive: duplicate seqno xxxxxx".  I'm not a TCP/IP expert, but in looking at normal traces, I see that the acknowledgment number in the ACK is the same as the sequence number in the packet being ACKed, and Wireshark clearly doesn't consider this to be a valid ACK to any previous packet.  Is there a good explanation for this?  If not, any pointers on how to track it down?  I know the stack is supposed to function; that's what makes this so frustrating.  192.168.0.112 is my computer, and 192.168.0.169 is lwIP 1.3.0.  
Also, are all those zeros at the end of the ACK supposed to be there? 

I've attached a trace.  Rename the extension to .zip. 

capture.piz
Description: Binary data