It's not that the license is self-contradictory, it's that the license text (as written here: http://php.net/license/3_01.txt) implies that the software is distributed only by the PHP Group, and is therefore not usable without modification by anyone outside the PHP Group. The solution is simple: modify the text of your project's license to have similar clauses to the PHP license, but not mention the PHP Group, OR re-license your software under the BSD license or another, similar license.