arriving one after each other on purpose as to avoid unwanted attention
Definitions (粵典–words.hk)
形容詞
兩個人為咗避嫌，於是分開咁喺唔同嘅時間到達或者離開同一個地方 describes how couples who wish to keep their relationship as a secret, so they will not enter or leave a building together; literally front and back legs
阿晴同老細近排成日行得好埋，雖然日日返工放工都係前後腳咁行，但係每次都係阿晴走咗冇耐，老細就會走。
阿晴同老细近排成日行得好埋，虽然日日返工放工都系前后脚咁行，但系每次都系阿晴走咗冇耐，老细就会走。
Ching and boss are very close recently. Although they aren't leaving or coming to work together, every time a few minutes after Ching leaves, boss would leave as well.
Definitions (Wiktionary)
noun, literally
front foot and rear foot
adv, informal
almost simultaneously; consecutively; successively
Ching and boss are very close recently. Although they aren't leaving or coming to work together, every time a few minutes after Ching leaves, boss would leave as well.