Mac Mini 2012 - dual band bluetooth?
I don't know if this answers your question but here:

Single-Chip Bluetooth® 4.0 HCI Solution with Bluetooth Low Energy (BLE) Support

The Broadcom BCM20702 is a single-chip Bluetooth processor with a high performance integrated 2.4-GHz RF transceiver. It is fully compliant with Bluetooth 4.0 and all prior standard features. The BCM20702 offers unmatched integration, including on-board memory for a very small footprint and low cost of implementing a Bluetooth system.  

Which i got from http://www.broadcom.com/products/Bluetooth/Bluetooth-RF-Silicon-and-Software-Solutions/BCM20702.
I got this from ifixit's Mac Mini Late 2012 teardown.