Fetches older post as new when a post is removed.

[fuzzfactory0]

Describe the bug
Every time a post is deleted from the subreddit you're watching, the Xth post on the subreddit will get reposted in your feed (Assuming X is the number of results configured in your code.)

To Reproduce
Steps to reproduce the behavior:

1. Submit more posts than the "results" config to a subreddit you're watching
2. Remove the latest post
3. See error

Expected behavior
Nothing. When a post is removed, it should do nothing.

Additional context
This happens because of how new posts are detected by comparing batches and removing duplicates. When a post is removed, the new batch will have an older post than every post in the previous batch, and that one is treated as new by the code.
Easy fix: compare timestamps between posts.

[brenapp]

Generally, there are a lot of unexpected behaviors that can come from setting results too low. Is snoostorm reissuing new events for posts it has handled in the past? Cause that is aberrant behavior. For now, until I can properly triage, setting results higher (usually 25 posts is good for all of reddit)

[brenapp]

So far, I've been unable to replicate this issue. Can you give me a minimal verified example?

[brenapp]

Cannot replicate, see if this issue is still a problem with snoostorm@1.4.0