This article explores the skill of bilingual infants who were learning Dutch and another non-tone language to distinguish tonal contrasts. All infants from 5 to 18 months of age succeeded in distinguishing a tonal contrast of Mandarin Chinese (Tone 1 versus Tone 4) and displayed a U-shaped pattern when facing a less acoustically salient manipulated version (contracted) of the aforecited contrast. Specifically, infants displayed initial sensitivity to the contracted contrast during their early months, followed by a loss of sensitivity at the stage where tonal perceptual reorganization typically happens, and a sensitivity rebound by the end of the first year after birth. Compared to a prior inquiry of the authors testing monolingual Dutch infants (Liu & Kager, 2014), the discrimination patterns of bilingual infants disclosed both resemblances and discrepancies. On one hand, as with monolinguals, non-tone-learning bilingual infants’ tonal perception proposed plasticity affected by contrast acoustic salience along the trajectory of perceptual reorganization; as well as a general U-shaped perceptual pattern when distinguishing non-native tones. On the other hand, bilingual infants seemed to recover sensitivity to the contracted tonal contrast at an earlier age (11–12 months) in comparison with monolinguals infants (17–18 months). This inquiry supplies divers explanations, stemming from the concurrent exposure to two languages, to account for the 6-month bilingual perceptual plasticity from linguistic and cognitive viewponts. The overall outcomes of the inquiry present insights into the infant perceptual reorganization and language development trajectory, extend on the differences between monolingual and bilingual language development, and widen the grasping of the impact of bilingual exposure to the perception of non-native contrasts in infancy from linguistic and cognitive viewpoints.