TYPO3 Core

Please post your emconf and composer.json here, so we can take a look.

Yes, we lack a concrete example of such a "doubled" extension to be able to reproduce. Thanks

haven't published this experimental extension yet. running this composer file from shell works fine.
could you please give a link to a documentation of the capabilities of the new packagemanager?

important part from composer.json:
"config": {
"vendor-dir": "Resources/Public"
},
"require": {
"Scottjehl/picturefill": "dev-master"
},
"repositories": [ {
"type": "package",
"package": {
"name": "Scottjehl/picturefill",
"version": "dev-master",
"source": {
"url": "https://github.com/scottjehl/picturefill.git",
"type": "git",
"reference": "origin/master"
}
}
}
]

important part from emconf:
$EM_CONF[$_EXTKEY] = array(
'title' => 'picturefill',
'description' => 'picturefill',
'category' => 'fe',
'state' => 'experimental',
'internal' => '',
'uploadfolder' => '0',
'createDirs' => '',
'clearCacheOnLoad' => 0,
'version' => '0.0.3',
'constraints' => array(
'depends' => array(
'php' => '5.3.0-5.5.999',
'typo3' => '6.2.0-7.0.999',
'css_styled_content' => '6.2.0-7.0.999'
),
),
);

PackageStates.php contains both:

'picturefill' => 
    array (
      'state' => 'active',
      'packagePath' => 'typo3conf/ext/picturefill/',
      'classesPath' => 'Classes/',
      'suggestions' => 
      array (
      ),
    ),
    'responsiveimages.picturefill' => 
    array (
      'manifestPath' => '',
      'composerName' => 'responsiveimages/picturefill',
      'state' => 'inactive',
      'packagePath' => 'typo3conf/ext/picturefill/',
      'classesPath' => 'Classes/',
      'suggestions' => 
      array (
      ),
    ),

I removed both entries from PackageStates and installed the extension again.
This time there exists only one entry "picturefill".

Good and bad news: I cannot reproduce this error.

Where does this "responsiveimages" (.picturefill) prefix comes from? Your composer states "Scottjehl" as vendor name.

Here is the entries in PackageStates.php I have with https://git.typo3.org/TYPO3CMS/Extensions/sphinx.git/blob/HEAD:/composer.json:

    'sphinx' => 
    array (
      'state' => 'active',
      'packagePath' => 'typo3conf/ext/sphinx/',
      'classesPath' => 'Classes/',
      'suggestions' => 
      array (
      ),
      'manifestPath' => '',
      'composerName' => 'causal/sphinx',
    ),

Entry is not doubled, composerName is referenced.

AFAIR you have to add "type": "typo3-cms-extension" to your extension's composer manifest to avoid the doubled entry.

Here is a minimal composer.json required for the package management to work properly:

{
    "name": "vendor/extention-key",
    "type": "typo3-cms-extension",

    "version": "1.0.0",

    "require": {
        "typo3/cms-core": ">=6.2.6,<8.0" 
    },

    "autoload": {
        "psr-4": {
            "Vendor\\ExtensionKey\\": "Classes" 
        }
    },

    "replace": {
        "extention_key": "self.version",
        "typo3-ter/extention-key": "self.version" 
    }
}