Something like this should do it.
| inputlookup yourlookup.csv | eval recentTime=0 | append [| metadata type=hosts index=* | table host recentTime ] | stats max(recentTime) as recentTime by host | eval Result=if(recentTime=0,"Not Received","Received") | convert ctime(recentTime)
Sounds like you have duplicates in your lookup file.
Do this to see:
| inputlookup yourlookup.csv | stats count, dc(host) AS unique_hosts
unique_hosts are not equal then find your duplicates:
| inputlookup yourlookup.csv | stats dc(host) AS unique_hosts by host | where host>1