This nostr:nprofile1qqsgydql3q4ka27d9wnlrmus4tvkrnc8ftc4h8h5fgyln54gl0a7dgspp4mhxue69uhkummn9ekx7mqpzemhxue69uhhyetvv9ujuurjd9kkzmpwdejhgqg4waehxw309aex2mrp0yhx6mmnw3ezuur4vgkhjsen is the real one.
Now, the question is, how do you know that's the real nostr:nprofile1qqsgydql3q4ka27d9wnlrmus4tvkrnc8ftc4h8h5fgyln54gl0a7dgspp4mhxue69uhkummn9ekx7mqpzemhxue69uhhyetvv9ujuurjd9kkzmpwdejhgqg4waehxw309aex2mrp0yhx6mmnw3ezuur4vgkhjsen?
Some clients are better about this than others.
You can tell, if you look at their npub instead of their display name, that they are two different Jacks, but determining which is an impostor takes a bit more digging.
One way would be to look at how many followers they have, and that would definitely work in this case. However, follower counts can be gamed. A determined impostor could set up a bunch of random npubs to follow their scam account to inflate the follower numbers.
Web-of-Trust and/or pagerank are the much better tools
For instance, if I go over to #Coracle and compare the two accounts, this is what I get:
Impostor Jack:

Real Jack:

And if you go to https://npub.world and search for "Jack," this is what you will get for your results using pagerank:

The real Jack is the first result, and no impostors are returned at all. And if we open up his profile there, we see this:

The real Jack has over 43k REPUTABLE followers. So not just random npubs that were spun up to inflate a following number, but actual users.
So we have the tools available to us to avoid following bots and scammers. We just have to know how to utilize them.
Thank you nostr:nprofile1qqsf03c2gsmx5ef4c9zmxvlew04gdh7u94afnknp33qvv3c94kvwxgspz4mhxue69uhhyetvv9ujuerpd46hxtnfduhszrnhwden5te0dehhxtnvdakz7qgewaehxw309a5xyu3wvdhhyctrd3jjuum0vd5kzmp0er5gcs for building WoT into Coracle for some time now, and thank you nostr:nprofile1qqs0dqlgwq6l0t20gnstnr8mm9fhu9j9t2fv6wxwl3xtx8dh24l4auspz4mhxue69uhkzat5dqhxummnw3erztnrdaksz9nhwden5te0d4kx26m49eex2ctv0yhxcmmv9uq3gamnwvaz7tmjv4kxz7fwv3sk6atn9e5k7dj6rpa and others with Vertex for building pagerank tools that I hope to see more clients adopt!