lit. to paint holding two brushes (idiom); fig. to work on two tasks at the same time
to attack one problem from two angles at the same time
Definitions (粵典–words.hk)
語句
為咗一個目標同時做兩樣嘢 to do two things at the same time in order to achieve a single goal; literally: "to paint a picture with two brushes at the same time"
我日日游水又跑步,希望雙管齊下減到肥。
我日日游水又跑步,希望双管齐下减到肥。
ngo5 jat6 jat6 jau4 seoi2 jau6 paau2 bou6, hei1 mong6 soeng1 gun2 cai4 haa6 gaam2 dou2 fei4. I swim and jog every day, hoping to lose weight by applying both methods at the same time.
Definitions (Wiktionary)
phrase, idiomatic
to use a two-pronged approach; to work along both lines simultaneously