You only need one of either dc(Account_Name) or by Account_Name to get that stats right, but you'll want the by Account_Name because it'll do what you need better. They you'll just have a where (or in this case, search would be fine*) after it.
index=wineventlog source="WinEventLog:Security" EventCode=4624 (src_ip=10.13.111.60 OR src_ip=10.14.111.60)
| stats dc(src_ip) AS distinct_sources BY Account_Name
| where distinct_sources > 1
That should do it.
Or change it to a search -
index=wineventlog source="WinEventLog:Security" EventCode=4624 (src_ip=10.13.111.60 OR src_ip=10.14.111.60)
| stats dc(src_ip) AS distinct_sources BY Account_Name
| search distinct_sources > 1
The main difference between search and where is that where lets you compare two fields, like where distinct_sources > myOtherfield , and search only searches one field against a string/constant/whatever. In this case, you are just searching for greater than some number, so...
Which brings up the time you'd need where - if you were to set a threshold (which isn't really that useful in this simple case, but can be useful in more complex ones), you could do something like
index=wineventlog source="WinEventLog:Security" EventCode=4624 (src_ip=10.13.111.60 OR src_ip=10.14.111.60)
| stats dc(src_ip) AS distinct_sources BY Account_Name
| eval threshold_of_badness = 2
| where distinct_sources >= threshold_of_badness
... View more