ISC says something like

Copyright © 2004-2013 by Internet Systems Consortium, Inc. (“ISC”)
Copyright © 1995-2003 by Internet Software Consortium

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED “AS IS” AND ISC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

But copyleft-next disallows additional conditions

When Distributing a Covered Work, You may not impose further restrictions on the exercise of rights in the Covered Work granted under this License. This condition is not excused merely because such restrictions result from Your compliance with conditions or obligations extrinsic to this License (such as a court order or an agreement with a third party).

However, You may Distribute a Covered Work incorporating material governed by a license that is both OSI-Approved and FSF-Free as of the release date of this License, provided that Your Distribution complies with such other license.

So I wonder if it is legal to create a derived work based on both ISC-licensed work and copyleft-next-licensed work.