Hi,
the is pretty old and was an OEM from Symbol I believe, with the single MAC as you mentioned, which caused a lot of devices to be confused.
In 2008 HP acquired Colubris, a dedicated wireless company, all these products are branded with "MSM" in the current portfolio.
All these APs (MSM3xx/MSM4xx) support 16 unique SSIDs (so they have 16 MACs per radio) and will give you a proper SSID to vlan mapping.
For the 5400, there is a controller, this is the MSM765zl module,
Best regards,Peter