No, you cannot sync two Wii U GamePads to a single Wii U console at the same time.
Why Only One GamePad Is Supported
Hardware Design: The Wii U was engineered to communicate with only one primary GamePad for control, display, and features.
Game Compatibility: Nearly all Wii U games were designed around a single GamePad; they would not function correctly with multiple.
Multiplayer Design: Additional players use Wii Remotes, Nunchuks, or Pro Controllers.
Alternative Controller Options
Wii Remotes & Nunchuks: Classic Wii controllers for multiplayer.
Pro Controller: Traditional gamepad experience.
Second GamePad as Display Only: Some games allow a second GamePad to act as a secondary screen (maps, info) while the primary GamePad controls the game.
