I assume by "seasoned" programmers, you mean ones that are entrenched at their current company. If so, then you must realize that they are there, because they are making more money then they deserve. They will mostly try to discredit their fellow employees in everything they do. Because, a discredited peer is one that won't be stealing their raise. You will be hearing lots of phrases with "since the beginning" and "experience" in them.
What you must do is to show no favor to one or the other. That way they will continue fight for a competitive advantage for review time. I'd also advise bringing in some extremely young programmer and sing his or her praises. Call the young programmer "hotshot" and "guru". There is nothing more that they will hate than this programmer. You can use this hate to blackmail them into working more. You may be able to even get them to do some overtime.
Blinding speed can compensate for a lot of deficiencies. -- David Nichols