Yes.
This is an example of turning the empire archivist into infinitely repeatable
<ImprovementType InternalName="F_Archivist">
<IgnoreDuplicateImpLimit>true</IgnoreDuplicateImpLimit>
</ImprovementType>
and this is an example of turning the number of repeatable buildings you can build in the capital city of empires, at level 2 only, into 4 instead of 2.
<ImprovementType InternalName="F_Capital_L2">
<CitywideDuplicateImpLimit>4</CitywideDuplicateImpLimit>
</ImprovementType>