Symptoms

Cannot resolve Service Instance References where package was created on single site collection but target has 2 site collections.
 

Diagnoses

In this scenario the package was created with multiple sites in a single site collection, this will package a single service instance as K2 only registers a service instance per site collection. On the target this sub site is its own site collection and when deploying the package only contains 1 Service instance and thus you can only map one.
 

Resolution

This is currently by Design in P&D, P&D doesn't have the ability to split a Service instance during deployment. It is a valid feature though and I have logged this internally. To get around this Dev instance will also have to use 2 Site collections then the package will have 2 Service instances to remap on the destination during deployment.