Getting the title is actually pretty straightforward — WPSSO uses the standard wp_title() and get_the_title() functions from WordPress. Themes and SEO plugins (like Yoast SEO) often hook into these functions to manage / customize the text. WPSSO does not hook these functions to modify the text — it uses what WordPress returns. I suspect your theme or another plugin is hooking these functions and may not be properly coded. Yoast SEO overrides the default title text (which you say is problematic) with a customized text of your choosing, so your solution may be more of a functional patch / work-around. WPSSO will use whatever text is returned by those functions.
I would have suggested you open a support thread or ticket for these issues. This problem does not happen often, but when it does, users can try unchecking the “Use Filtered (SEO) Title” option on the Advanced settings page. WPSSO will then try to save the original title value before any theme / SEO plugin hooks can get to it. Obviously this is an Advanced function, so only available to Pro users.
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