There is a difference in tags usage when somebody modifies an event.
Some developers use @change, others use @changed.
Official documentation http://www.phpdoc.org/docs/latest/references/phpdoc/tags/since.html suggests adding more than one @since tag.

> This tag can occur multiple times within a PHPDoc. In that case, each occurrence is treated as an entry to a change log. It is RECOMMENDED that you also provide a description to each such tag.