From Kong Rong's
《荐祢衡表》 (Han dynasty):
飞辩骋辞,溢气坌涌,解疑释结 - recommending the brilliant Mi Heng for being able to 'soar in argument and untie every doubt.'
释 and
解 are near-synonyms ('to loosen, to untie'); the four-character structure is a rhetorical doubling for emphasis.