The couple of percent deals tend to be settlements. The injunctions are always from successful lawsuits. I'm guessing that any potential infringement is ambiguous enough so that both sides decide to settle. But really this is no more than a wild guess - I have no idea what processes Amphastar (or Teva) use (and neither does MNTA).
One issue for MNTA here is timing - could be that the Amphastar process predates the MNTA patents.