Acts 12
Yes, there are 2 different men named James in this chapter:
- James the son of Zebedee (brother of John, one of the original 12 apostles, aka James the Great)
- James the son of Joseph (prominent figure at the Jerusalem Conference of Acts 15, aka James the Lord's brother aka James the Just)
Prior to the death of James the son of Zebedee, every mention of a man named "James" in the book of Acts comes with a disambiguation (e.g. James is associated with his brother John, or James the son of X is used as a descriptor). After the death of James the son of Zebedee, the name "James" is never disambiguated; the reference is always just to "James".
James was a common name. The lack of disambiguation after Acts 12:2 indicates that the author didn't need to disambiguate anymore; the audience already knows to whom the author refers -- this is only possible if there is a man named James who is far more prominent than any other James. This level of prominence is clearly applied to James the Lord's brother by Paul in Galatians 2:9 (which describes a meeting that definitely occurred after the death of James the son of Zebedee)1. This James' prominence is also attested by Josephus in Antiquities 20.9.
Note that exactly the same thing happens in Luke 24:34 with reference to Simon (Peter)--there are a lot of Simons, but one is by far the most prominent and requires no disambiguation.
This pattern of communication is readily testable. For example, I’ve worked in multiple office environments where there were several people named John, including the top boss. I noticed a pattern. When people were talking with one of the Johns, they just called him John. When they were talking about a John, the top boss was just “John”, whereas all the other Johns were “John X” or something like that. The most prominent individual with the name was the one who needed no introduction, all the other Johns were disambiguated from him, not he from them.
The prominence concept is also one of the reasons the James of the Epistle of James is usually held to be James the Lord’s brother. After the death of James the son of Zebedee, James the Lord’s brother is frequently referred to as just “James”, suggesting he was the most prominent Christian man of the time bearing that name. He was the James who needed no introduction, hence no need to disambiguate himself from other people named James when writing his epistle.
--
1 Cor 15
The James referred to by Paul in 1 Corinthians 15:7 is understood to be James the Lord's brother:
- James the son of Zebedee & James the son of Alphaeus have already seen Him--see verse 5 (yes Cephas gets a double mention but only because he saw the Lord before the other apostles did, see Luke 24:34)
- James the Lord's brother apparently was not a believer during Jesus' ministry (John 7:5, Mark 3:21) but later became a prominent teacher & leader in the Christian faith who could be appealed to as a credible source. The appearance of the resurrected Lord is generally understood to have been a significant event in his conversion (though this is more explicit in extra-Biblical sources it is only implicit in the Bible)
- Paul habitually refers to James the Lord's brother without disambiguation
- In 1 Cor 15 Paul is listing witnesses of the resurrection whom the audience can consult to fact-check the story for themselves (see further discussion here); The other very prominent James in early Christianity--James the son of Zebedee--died circa AD 44, before 1 Corinthians was written (AD 54 or 55). James the Lord's brother died in AD 62 (Josephus Antiquities 20.9) and was still alive when Paul wrote to the Corinthians.
1 - Galatians 2 probably describes the Jerusalem Conference of AD 49. However, even if it is understood to be a conference before Paul's first missionary journey (circa AD 46) rather than after, it's still too late to be within the lifetime of James the son of Zebedee: he was put to death by Herod Agrippa I, who died in AD 44.