Duplicate Purge errors on Dashboard for AutoBlog

Hi,
We have these site from this data feed sources http://wp.nyu.edu/libux/feed/ & https://nyudataservices.wordpress.com/feed/ to data feed receiver https://wp.nyu.edu/librariesandblogs.
We are seeing multiple duplicate PURGE errors in the logs and the Dashboard also shows CURL ERROR 51.
These are the following logs we found related to that:
2017/04/21 22:53:15 [error] 3634#0: *34415709 [lua] purge.lua:34: duplicate purge for: 10.0.6.169::disappointed:libux/tools-of-the-trade-user-testing-with-lookback-io/, client: 10.0.2.59, server: , request: "PURGE /libux/tools-of-the-trade-user-testing-with-lookback-io/ HTTP/1.1", host: "10.0.6.169", referrer: "http://10.0.6.169/libux/
2017/04/21 22:53:15 [error] 3634#0: *34415715 [lua] purge.lua:34: duplicate purge for: wp.nyu.edu::disappointed:, client: 10.0.2.59, server: , request: "PURGE / HTTP/1.1", host: "wp.nyu.edu", referrer: "http://10.0.6.169/"
2017/04/21 22:53:15 [error] 3634#0: *34415721 [lua] purge.lua:34: duplicate purge for: wp.nyu.edu::disappointed:slight_frown:.*)(/?)feed(.*), client: 10.0.2.59, server: , request: "PURGE /(.*)(/?)feed(.*) HTTP/1.1", host: "wp.nyu.edu", referrer: "http://10.0.6.169/(.*)(/?)feed(.*)"

Can you please investigate why does this happen? Only I can find is that whenever the it runs to collect feeds it also throw PURGE requests to remove the data from cache.
So Please let us know the cause of this issue?