Setting Value Set to Strange Number

To put this as quickly as possible, my Computer layer settings specify to avoid using "this" qualifiers and show a warning if they are used.  However, the main solution I work in at my company has a Team Settings layer specifying to always use "this" for the current and base class members, and throw a warning if it's not there.  While working in this solution, I noticed it was warning me to delete the "this" qualifiers, which was incorrect since the Team settings should have overridden my personal preference.  When I looked in the Team Settings file, I saw this line:

<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpCodeStyle/ThisQualifier/INSTANCE_MEMBERS_QUALIFY_MEMBERS/@EntryValue">15</s:String>

What is the meaning of the value 15?  Did someone on my team accidentally make this as a manual edit?  I was able to fix the issue by changing the line to:

<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpCodeStyle/ThisQualifier/INSTANCE_MEMBERS_QUALIFY_DECLARED_IN/@EntryValue">ThisClass, BaseClass</s:String>

Is it possible ReSharper entered that 15 value at some point?  And if so, why?