Hi Daniel,
A single head/tail message does appear:
Aug 28 03:42:09 gw1 /usr/local/sbin/kamailio[7913]: : <core> [mem/q_malloc.c:159]: qm_debug_frag(): BUG: qm_*: prev. fragm. tail overwritten(3630643536313a64, 2d303634622d3965)[0x7f99b713d008:0x7f99b713d038]!
Shortly before a crash.
-- Alex