Without going into details and with a hope that you won't get curious, I have few questions. 

No comments as to whether the signature can over lap the words if you copy and paste the signature from another source?

Frozen....layers with transparency would allow you to do that....

Layers of transparency? Can you please explain? How easy it for a regular person do it? I cannot do it. I can scan a document with this signature and then copy and paste it on another document, however, how can I make it overlap the words without hiding the words? If the copied signature is in png format I see it possible but if in jpeg it is impossible, unless you can somehow convert jpeg into png. Is that so easy?

Can I email you with more details?
Thanks

It's very easy. Photoshop can convert from jpeg to png (with transparency) then you can use the eraser tool (or the magic eraser tool) to remove the backfground whitespace. The new transparent image can be layered over the other.

In the examples you show however there are slight variations in the ink, lines and shapes. Enough for me to think it's not a duplicate. That said...I have no idea what you're getting at here....but I'd think about connecting with an attorney, handwriting expert, etc. I also ALWAYS ask for hard copies on all documents.

Thank you. We have a handwriting expert. In short: The originals were destroyed by someone who does not want these two documents to exist. However, the copies exist. This same person is now saying that these are fakes. The signatures were copied and pasted from another source.

Both the signatures are different from each other. We have another documents (possible "source"") that have signatures with very minor variations. Therefore, I thought I ask you guys about how easy it is to copy and paste a signature and let it over lap the words without hiding them underneath. However, from what I understand, it is easy to do that if you with photoshop.

Yes it is. However, the variations in lines, distances, etc in your example would be MUCH more difficult to duplicate.

Sorry for the delayed response...Steven hit the nail on the head...it's not that difficult to do...as to how hard it is for an average person to do...really depends on how well they can read and follow directions...a simple search for transparency and png files with the program you are using should give you easy to follow directions...

Anything else you can think about?

If I want someone to testify about this in the court who should I look for (experience, profession) etc? I want someone from Los Angeles.