To resolve this issue, assign a unique value for the Property tag attribute ovf:key for each VirtualSystem.
For example:
Change the ovf:key values from:
<Property ovf:key="<B>IP Address" ovf:type="string" ovf:userConfigurable="true" ovf:value="IP_Address_1">
<label>IP Address VM1</label>
<Description>IP Address VM1</Description>
</Property>
<Property ovf:key="<B>IP Address" ovf:type="string" ovf:userConfigurable="true" ovf:value="IP_Address_2">
<label>IP Address VM2</label>
<Description>IP Address VM2</Description>
</Property>
to:
<Property ovf:key="<B>IP_Address_VM1" ovf:type="string" ovf:userConfigurable="true" ovf:value="IP_Address_1">
<label>IP Address VM1</label>
<Description>IP Address VM1</Description>
</Property>
<Property ovf:key="<B>IP_Address_VM2" ovf:type="string" ovf:userConfigurable="true" ovf:value="IP_Address_2">
<label>IP Address VM2</label>
<Description>IP Address VM2</Description>