Steps to reproduce the issue

when i add an variable request for my component, if i select "editor" field type with this code:
<field name="description" type="editor" label="Description" description="Description of product." filter="safehtml"/>
or i select another filter attribute for editor , can't correctly save

Expected result

save correctly

Actual result

after save all break lines are convert to double underline.
for example , this code:
<p>Lorem Ipsum</p>
<p>Dolor sit ammet</p>
is convert to:
<p>Lorem Ipsum__Dolor sit ammet</p>

System information (as much as possible)

PHP Built On Windows NT SYSTEM4 6.1 build 7601 (Windows 7 Ultimate Edition Service Pack 1) i586
Database Version 5.6.17
Database Collation utf8_general_ci
Database Connection Collation utf8mb4_general_ci
PHP Version 5.5.12
Web Server Apache/2.4.9 (Win32) PHP/5.5.12
WebServer to PHP Interface apache2handler
Joomla! Version Joomla! 3.6.2 Stable [ Noether ] 4-August-2016 23:41 GMT
Joomla! Platform Version Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
User Agent Mozilla/5.0 (Windows NT 6.1; rv:48.0) Gecko/20100101 Firefox/48.0

Additional comments

all editors in module parameter , plugin parameter , joomla article and etc... are correct,but just in this section not work.
Tested on Joomla 3.6.0 and 3.6.2