Should this second copy of the note with stamped endorsements be presented as fraud on the court?
Your question is the reason it is very difficult to give any thoughts or opinions about someone's case on line. I don't think anyone can give you an opinion without seeing the documents.
My knee jerk reaction without seeing EXACTLY what is on the documents would be, NO. I don't think it is fraud upon the court, and I think it could easily explained away. It could have very easily been a simple paperwork mistake.
The long answer would be you need more focused discovery and to start reading the cases in your jurisdiction. What the Plaintiff gives you in discovery can be used by you as evidence, it is NOT evidence, and it cannot be used to support the Plaintiff's case. If you chose NOT to use discovery responses in court they just sit in a pile on your desk. You obviously would NOT want to use documents or responses that have a negative effect on your case.
On the flip side, I would encourage you to read the cases on pleadings being judicial admissions, denying the authenticity of exhibits, and denying averments in the pleadings. Most of the time what you put in your pleadings (complaint) is a Judaical admission. This includes your exhibits. The court does not need to accept as true averments that are contradicted by exhibits attached. In some jurisdictions you cannot deny the authenticity of your own exhibits.
This can cause problems and questions of facts for the court.
Rather than trying to say a paper work mistake (that's what they will say) is fraud upon the court, I personally would first be looking at are they binding themselves to something negative with the complaint? I do think you are raising a question of fact in regards to did they have the original note when they filed suit and exactly when did they receive it. If you focused some discovery asking them to authenticate the note attached to the complaint as a true and correct copy and probe some more on when it was received, from whom, ect... you may box them in a little. If they admit that the copy attached to the complaint is true and correct, they were the holder the whole time, where did the endorsements come from? It obviously had to be sent to the other entities for endorsement. When they received the note THEY became the holder for how ever brief a time it took them to do the endorsement. With good discovery and some answers under oath you may get them pretty twisted. I've seen a few bankruptcy cases where this has happened. The bank said they had the note at all times but the evidence showed other parties did hold the note in the same period.
If the endorsements are totally different, it really raises a question of did they have the original at commencement.
It is pretty difficult to say you have the original and deny the authenticity of the copy you attached to the complaint.
I don't think you are going to have much success with fraud at this point...you need more discovery answered under oath.
Not legal advice.......Just a few thoughts......