It's important to note that you are linking to dbpedia's version of Wikidata, as noted in the other question, and they might have done things a little differently when processing it. I can't really answer from the dbpedia side of things, so this is a Wikidata-oriented answer...
The Wikipedia pages you mention link to the same item, https://wikidata.org/wiki/Q186509 - the other item links to a related set of WP pages, in English "Mathematical constants by continued fraction representation". However, this item has had its Chinese label truncated (it lost the brackets in 数学常数 (以连分数表示排列)) and so it shows up on Wikidata with the same Chinese label as the first.
If you are simply matching on labels or aliases, then the key thing to know is that Wikidata's labels and aliases are not unique. There might be a hundred items with an identical "John Smith" label in English and fifty more with that alias. In general, Wikidata does not keep the disambiguation notes in brackets from Wikipedia page titles, which is probably why the Chinese one here lost the bracketed section, but there can be many other differences.
You can get a copy of the full set of the interlanguage links from the Wikidata dumps at https://dumps.wikimedia.org/ - you will want the wikidatawiki dump and the wb-items-per-site file ("For each Wikidata item, this contains rows with the corresponding page name on a given wiki project."). Documentation for the file is at mediawiki.org and more general documentation on the dumps is available on Wikidata.
