How "match" operation works in "Association Ruleset" when I creat an alert-cheks?

I'm using "device group (free)" for the "Association Ruleset" to create and alert cheks. Due there is not "regex" option, I select "match", I would like to know how that operation works because It looks like doesn't work properly. In my case, this is the case:

Groups:

• Node A - City1 - N001
• Node B - City1 - NP01
• Node C - City1 - N001
• Node D - City1 - N001
• Node F - City1 - NP01
• Node G - City1 - N001
• Node H - City1 - NP01
• Node J - City1 - N001

I want to match the groups that contain "City1 - N0", so I use:

match City1 - N0

But this alert-cheks also match the group that contain "City1 -NP"

Why this happen??