How we cite our quotes: (Section.Paragraph)
Quote #1
[…] we, your Majesty's most dutiful and loyal subjects, the commons of Great Britain in parliament assembled. (1.2)
This line, from near the beginning of the law, is asserting Parliament's legitimacy. Basically, it's like, "here's why we get to make this law." It wasn't even unusual. Any law of the time would include a passage like this.
Quote #2
And be it further enacted by the authority aforesaid, That the commissioners for managing the said duties, for the time being, shall and may appoint a fit person or persons to attend in every court of publick [sic] office within the said colonies and plantations. (13.1)
This section grants legitimacy to employees. It's practical, sure, but it also traces the locals actually collecting the stamp duties all the way back to the king.
Quote #3
And it is hereby declared, That upon any prosecution of prosecutions for such felony, the dye, tool, or other instrument made use of in counterfeiting or forging any such seal, stamp, mark, type, device, or label, together with the vellum, parchment, paper, cards, dice, or other matter, or thing having such counterfeit impression, shall, immediately after trial or conviction of the party or parties accused, be broke, defaced, or destroyed, in open court. (20.1)
The stamp itself was a symbol of legitimacy. So anyone forging it was ordered put to death. This section talks about what to do with the actual forged stamp itself. The idea was to mess it up enough that it could no longer function for its intended purpose. This did help discourage later forgers, but it also reasserted the legitimacy of the real stamps.
Quote #4
And it is hereby further enacted by the authority aforesaid, That no person whatsoever shall sell or expose to sale any such pamphlet, or any news paper, without the true respective name or names, and place or places of abode, of some known person or persons by or for whom the same was really and truly printed or published, shall be written or printed thereon; upon pain that every person offending therein shall, for every such offence [sic], forfeit the sum of twenty pounds. (27.1)
Legitimacy requires identity. In this case, you're not looking at legitimacy for the crown but for people subject to the law. Basically, something that would list authorship, like a newspaper, has to have a person's right name on it. This keeps track of the duties owed and it also makes the paper itself legitimate.