Is it grammatical to end a sentence with two dots? Because this involves a particular type of sentence, let me give you an example.
For example:
The meeting was to begin in 8:00 p.m..
This is not a matter of grammar. Using s single or double period here does not change in any way the usual parsing or pronunciation of the sentence.
Whether to use an additional period to end a sentence which ends in an abbreviation or name or some other element incorporating a period in its customary orthography is a matter of style. Adhere to the discipline of your editor, publication, or organization, or in the absence of a house style, adopt a style manual appropriate to your audience and tastes and be consistent in its application.
With that preamble out of the way, I would say that it is uncommon to see a double period / full stop in any variety of standard written English i am familiar with.
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2Its also generally less common to see initialisms and acronyms use periods these days, instead favoring capitalization. I would write that as 'The meeting was to begin in 8:00 PM.', but that is not formally correct. – Frank Thomas Jun 12 '19 at 4:24
