In V2.9 we changed the MSH-6 (Receiving Facility) RP/# value to Y (cardinality 0..*). That change was not present in the 2017 January ballot but was added in the 2017 September ballot. I couldn't find a record of that change, there are no votes about it in the 2017 January ballot results, and it isn't mentioned in the list of changes in 2017 September ballot. I suspect the change was introduced accidentally without following the proper process and thus it should be rolled back as a technical correction.
This change has introduced a discrepancy with MSH-5 (Receiving Application) which does not have RP/# set to Y (cardinality 0..1). Even if it is potentially valid to send the same message to multiple facilities, those separate facilities won't share the same application.