Combining MediaWiki API:Users and API:Usercontribs - api

Question

I have a list of users. I am trying to retrieve their registration, editcount and gender using API:Users, and contribution data using API:Usercontribs.
Because of being gentle with the API, I have to put a bunch of usernames in each request, and I need to match their userIDs in order to be able to merge the results from the two APIs.
I faced an strange problem: there are a fair number of users with different userIDs retrieved by each method. E.g., if you query data for username "December21st2012Freak" from API:Users, you'll get userID 14281125, but requesting the same username from API:Usercontribs, the userID returns as 10141256.
Another example is username "The Sunshine Man", which has userID 4857299 retrieved bu API:Users and userID 4302884 retrieved by API:Usercontribs.
I don't understand why there is such an inconsistency.
Here are exact queries:
https://en.wikipedia.org/w/api.php?action=query&list=users&ususers=December21st2012Freak|The%20Sunshine%20Man&usprop=blockinfo%7Cgroups%7Ceditcount%7Cregistration%7Cemailable%7Cgender
which returns:
{
"query": {
"users": [
{
"userid": 14281125,
"name": "December21st2012Freak",
"editcount": 0,
"registration": "2011-03-29T02:14:36Z",
"groups": [
"*",
"user"
],
"emailable": "",
"gender": "unknown"
},
{
"userid": 4857299,
"name": "The Sunshine Man",
"editcount": 0,
"registration": "2007-07-13T20:00:58Z",
"groups": [
"*",
"user"
],
"gender": "unknown"
}
]
}
}
And the Usercontribs query:
https://en.wikipedia.org/w/api.php?action=query&list=usercontribs&ucuser=December21st2012Freak&uclimit=3&ucdir=newer&continue=
which results:
{
"batchcomplete": "",
"continue": {
"uccontinue": "20090904033705|311775264",
"continue": "-||"
},
"query": {
"usercontribs": [
{
"userid": 10141256,
"user": "December21st2012Freak",
"pageid": 24217201,
"revid": 311775169,
"parentid": 0,
"ns": 3,
"title": "User talk:MsD723",
"timestamp": "2009-09-04T03:36:13Z",
"new": "",
"minor": "",
"top": "",
"comment": "Added welcome template to user talk page. using [[WP:FRIENDLY|Friendly]]",
"size": 1458
},
{
"userid": 10141256,
"user": "December21st2012Freak",
"pageid": 24217203,
"revid": 311775198,
"parentid": 0,
"ns": 3,
"title": "User talk:Oneseeker2",
"timestamp": "2009-09-04T03:36:32Z",
"new": "",
"minor": "",
"top": "",
"comment": "Added welcome template to user talk page. using [[WP:FRIENDLY|Friendly]]",
"size": 1458
},
{
"userid": 10141256,
"user": "December21st2012Freak",
"pageid": 24217208,
"revid": 311775231,
"parentid": 0,
"ns": 3,
"title": "User talk:Carolynhinchey",
"timestamp": "2009-09-04T03:36:46Z",
"new": "",
"minor": "",
"top": "",
"comment": "Added welcome template to user talk page. using [[WP:FRIENDLY|Friendly]]",
"size": 1458
}
]
}
}
And
https://en.wikipedia.org/w/api.php?action=query&list=usercontribs&ucuser=The%20Sunshine%20Man&uclimit=3&ucdir=newer&continue=
which results:
{
"batchcomplete": "",
"continue": {
"uccontinue": "20070517145725|131549160",
"continue": "-||"
},
"query": {
"usercontribs": [
{
"userid": 4302884,
"user": "The Sunshine Man",
"pageid": 11271016,
"revid": 131518067,
"parentid": 131517319,
"ns": 4,
"title": "Wikipedia:Miscellany for deletion/Portal:Aquinas College, Perth",
"timestamp": "2007-05-17T11:48:17Z",
"comment": "/* [[Portal:Aquinas College, Perth]] */ Delete",
"size": 1773
},
{
"userid": 4302884,
"user": "The Sunshine Man",
"pageid": 7797923,
"revid": 131547208,
"parentid": 131525587,
"ns": 3,
"title": "User talk:Ryan Postlethwaite",
"timestamp": "2007-05-17T14:47:29Z",
"comment": "HeHe",
"size": 49019
},
{
"userid": 4302884,
"user": "The Sunshine Man",
"pageid": 11247929,
"revid": 131547970,
"parentid": 131543922,
"ns": 4,
"title": "Wikipedia:Requests for adminship/Bobak",
"timestamp": "2007-05-17T14:51:19Z",
"comment": "Support",
"size": 16492
}
]
}
}

Answer 1

As reported by Tgr: this is a bug, please be patient and wait for it to be fixed. https://phabricator.wikimedia.org/T99929