I want to ask, can a single user have multiple location signature but just one in signature panel ?
it is possbile ?
Yes that is possible however forbidden starting with PDF Spec 2.0. In smaller PDF versions it is possible to have one signature field (what you call "just one in signature panel") with multiple widgets.
There are several threads here on SO describing it in more detail: Here, here and here.
Please note that the examples are using iText as a PDF library. (So the code using PDFBox looks different and might not be possible out of the box)