I think there was a distinction between a deserter who switched sides and a prisoner of war who switched sides. There were promises made to those POWs on their new enlistment and who they were to fight and how they were to serve. The POWs, in most cases, were asked to switch sides by the governments who had control over them-- their skills were needed elsewhere. An out-right deserter was taking his own chances on how he would be treated by his new employer and in some cases were refused...many were not trusted by either side and were shunned.