John the Disciple and John the Elder

Eusebius of Cesarea writes (Church History, Book 3, Chapter 39) > In these words, it is noteworthy that Papias lists the name John > twice. The first time he includes John with Peter, James, Matthew and > the other apostles; he obviously means the evangelist. The second > time, in a new sentence, he includes John in another category, which > is different from that of the apostles; he places Aristion before him > and expressly calls him a presbyter. This proves the report true that > in Asia two disciples had the same name, and that in Ephesus two tombs > were erected, each of which still bears the name John. This must be > taken into account. For it is probable that, if one does not want to > think of the first John, the second saw the revelation that went under > the name of John. John's name, the second has seen the revelation that > goes under John's name. Papias, whom we have just quoted, confesses, > received the teachings of the apostles from their disciples, and heard > Aristion and the presbyter John personally. The thesis has been disputed; see SE anwer to https://christianity.stackexchange.com/questions/17428/who-wrote-the-book-of-revelation My question: Are there any independent sources available that support Eusebius thesis that John the Disciple and John the Elder were two different persons? I read in aforementioned article: "But Zahn and most Catholic writers agree that Dionysius was mistaken about the tomb". I could not identify the citation; in the writings of Dionysius I have only found passages about the tomb of Jesus. Have the two tombs in Ephesos been mentioned or even been identified?