First, the graphs
In the charts posted, the blue line shows the proportion of 90's registered to vote. The orange bars show the actual number of 90's registered to vote.
Although the two graphs are scaled the same as each other, they use a different scale on the left as on the right, and the data compiler has fixed the scales so that on the "Democrat counties" (top) graph the blue line is above the bars, and on the "Other counties" (bottom) graph, the blue line is below the bars.
This gives the false impression that the Democrats somehow have "dead people" voting. This is false also for other reasons:
The graphs do not show how many people actually voted.
Each graph shows essentially the same data but presented differently.
There is no data for any other age group to compare with.
The graphs below are redrawn so that data are separated back to different graphs, and now like is compared with like.
They show that there were more 90+ people registered to vote in "Other" counties, but that the proportion per 100,000 population is more in "Democrat" counties, in other words the density of 90+ voters is greater in "Democrat" counties.
They say nothing about any discrepancy between the number of registered voters and the number of votes cast. They reveal nothing about a supposed Democratic plot, as there is a large increase in voters from all counties.
Second, the table of voters
The data can be seen in the public records of Pennsylvania at
The table in the question showing just 11 voters born before 1900 is exactly the same as the 11 voter registrations shown in the Pa. data table, when ordered by DOB. So here is the source.
The table is headed
- 2020 General Election Mail Ballot Requests
and the column headings support that. The second column (not shown by OP) is
- Applicant party designation
which reveals that of the 11 records selected 3 were Republican and 8 were Democrat. This suggests the reason for them may have nothing to do with fraud attributable to any party.
There is also a group of records dated 1/1/1800, again with a variety of party designations. The reason for these is clearly administrative: the web page states that 1/1/1800 is used as a placeholder for privacy reasons.
Considering how few registered voters there are who are unreasonably old, the reason is far more likely to be clerical than fraudulent.
The data is about mail-in votes. It is well known that the number of mail-in votes has increased dramatically this year due to covid-19, and it is also known that Republicans were dissuaded from voting by mail. Here is one report from npr dated August 2020.
So this is where the apparent big increase comes from: mail-in registrations. Although the graphs are for the over-90s, I expect that there is an increase across all age ranges in 2020.
Back to the question: Were a large number of votes from suspiciously old Pennsylvanians received in the 2020 US presidential election?
Since the evidence to support that claim shows only age 90+ voting registrations, the presumption is that the data is presented to make it seem that way.
Just 11 records out of about 3 million is not a 'suspiciously large number'.