This issue is resolved in latest version of ORM Designer.
Based on this article http://www.php-fig.org/ we changed default spacing for all Doctrine2 projects to four spaces.
If anyone will want to update this settings manually, you can edit file Doctrine2.export.osc at line 162
phpResult.ReformatAst(true,110,"\n"," ");
and modify last parameter to any other value. Syntax of this command is
ReformatAst(reformatModifiedElementsOnly, maximumCharsOnLine, defaultNewlineChar, defaultLineIndention);