I verified that the JS code is only adding the picklist once. Skuid is adding the temp record ID to the picklist automatically. Is this a known issue?

When there should only be one picklist value:

console.log('picklist ' + field.metadata.picklistEntries.length);   // this prints out 1 correctly

field.element.empty();

skuid.ui.fieldRenderers.PICKLISTIfield.mode]( field, selectedCodeId );

When there should only be 0 picklist value:

console.log('picklist ' + field.metadata.picklistEntries.length);   // this prints out 0 correctly

field.element.empty();

skuid.ui.fieldRenderers.PICKLISTIfield.mode]( field, selectedCodeId );

So the issue appears from the skuid.ui.fieldRenderers.PICKLIST, which always adds the extra temp record Id!

This is now fixed by checking if the picklist value being added is available in the meta data. Thanks.