REST __next endpoint /w Duplicate ListItems

Question

Using REST connection with $top=20&$orderby=year
The problem occurs when the next 20 is fetched using the json.d.__next endpoint.
Some of the ListItems are sent again by SharePoint, resulting in duplicate ListItems, and confirmed using Fiddler.
I can only assume something is wrong on the SQL Server, no idea how to fix this.
Ideas?

Answer 1

Just confirmed that this is a problem in SharePoint Online as well, but with different results.
Creating the RESTful URL return the first 10 ListItems as expected:
...-public.sharepoint.com/_api/web/Lists(guid'57d26Aeb-7ab3-45c3-a96b-a6c8ed2aea58')/Items?top=10&$select=Title,Year,Quarter&orderby=Year,Quarter
Now using the __next URL returned for the REST query above:
...-public.sharepoint.com/_api/web/Lists(guid'57d26Aeb-7ab3-45c3-a96b-a6c8ed2aea58')/Items?%24skiptoken=Paged%3dTRUE%26p_ID%3d10&%24top=10&%24select=Title%2cYear%2cQuarter&orderby=Year%2cQuarter
This returns more than 10 more items and with more fields than specified in the '$select' and also includes duplicates from the first query, so actually SharePoint Online is a worse result then the SharePoint on-premise; which returns specified fields and
length just with duplicate ListItems.
To Repro create a custom list:
Title,Year,Quarter
A,2000,Q1
1,2000,Q1
B,2000,Q2
2,2000,Q2
and many more, and execute REST query then use the __next URL returned, and bad thing happen.
Sickening SharePoint still doesn't work after all these years.
Madness.