Why did Henry Clay group resolutions in pairs during the compromise of 1850?

Five questions were disputed between the pro and anti slavery factions, three developing as a result of the land conquered from the recent War with Mexico--Should California enter the Union as an antislavery state, should the remaining unorganized western territory allow slavery, should the western border of Texas, which abutted the newly conquered territory, be moved east to disallow slavery, should the slave trade be abolished in the District of Columbia, and should a new fugitive slave act be passed.  Henry Clay presented a resolution which would concede two questions to slave states, two questions to antislave states, and compromise on the fifth question.  These resolutions were passed as 5 separate bills, and collectively became the Compromise of 1850.  Concessions to the North were that California came in as an antislave state, and the slave trade was abolished in DC. The western territories were allowed to determine the slavery question for themselves and a strict fugitive slave law enacted; these were concessions to the South.  Texas was compelled to move its border East. The balancing act postponed the outbreak of civil war for a decade, but also planted the seeds of the Compromise's destruction, notably in deferring the question of slavery in the Territories, which lead to "Bleeding Kansas" 4 years later.

Encyclopedia Britannica, 11th ed., vol. 6,  pg. 814.