Not sure I get your explanation HF, we got that too
<GameModifier>
<ModType>CityDefenseSummon</ModType>
<Attribute>SummonUnitByClass</Attribute>
<Value>2</Value>
<Provides>+2 City Archer Party's</Provides>
<UnitClass>CityArcher_Party</UnitClass>
</GameModifier>
In some others buildings, are you saying that only 1 of the 2 requested archers will pop up?