The Music Quest 2Port/SE occupies an interesting spot in MIDI history. To answer your question directly: no, it is not "Roland MPU-401 compatible" in the way most vintage enthusiasts mean today (Intelligent Mode).
While Music Quest’s ISA cards (like the PC MIDI Card) were famous for being 100% Roland-compatible clones, the 2Port/SE is a parallel port (printer port) interface that uses Music Quest's proprietary MIDIEngine technology.
1. Is it MPU-401 Compatible?
Hardware Level: It is not a hardware MPU-401 clone. Because it connects via the parallel port rather than the ISA bus, it cannot "map" itself to the standard MPU-401 I/O port (330h) and IRQ (2/9) at a BIOS/hardware level.
Software Level (Windows): In Windows 3.1 through Windows 98, it is effectively compatible because Music Quest provided drivers that allow Windows to see it as a standard MIDI device. Any Windows software using the "MME" (Multimedia Extensions) API will work fine.
DOS Level (The Dealbreaker): It will not work with DOS games that specifically look for an "Intelligent Mode" MPU-401 (like Gateway or early Sierra titles). It requires specific driver support within the application (e.g., Cakewalk for DOS or Voyetra).
2. Did the packaging/manual claim compatibility?
The marketing language was very carefully phrased to avoid lawsuits while still attracting Roland users.
The Claims: The packaging and manual typically branded it as a "Professional MIDI Interface for IBM compatibles." Rather than claiming to be an MPU-401, they marketed it as an alternative or an upgrade to the MPU-401 standard.
"Industry Standard" phrasing: You would often see phrases like "Compatible with all Windows multimedia software" or "Supported by leading sequencers."
The Nuance: Music Quest often highlighted that their PC MIDI Card (the ISA version) was "100% MPU-401 compatible," which sometimes led to consumer confusion. However, for the 2Port/SE, the manual focuses on its MIDIEngine architecture, dual ports (32 channels), and SMPTE sync capabilities—features the original MPU-401 lacked.