This study builds on our previous research and provides additional analyses to determine if there is a relationship between the ability to process consonant length in familiar and unfamiliar languages for learners of Japanese whose native language is Italian or Mandarin. The emphasis is on L2-L3 (second-third language) phonetic influence. Japanese and Italian use consonant length contrastively, but not Mandarin. We thus asked if Mandarin learners with higher proficiency in Japanese are more or less accurate in length identification than Italian learners with first language (L1) experience of consonant length. Specifically, we focused on finding out if learners who accurately identify Japanese consonant length might also be accurate in their identification of the length category in Italian. Four groups of listeners differing in their L1 (Italian x 2 groups, Japanese, Mandarin) and experience with consonant length participated in forced-choice identification experiments. L1 Japanese and L1 Italian listeners identified the length category more accurately in their L1 than in the foreign language (FL). The ability to identify consonant length in Japanese and Italian by 18 advanced Mandarin-speaking learners of Japanese seemed unrelated. This suggests that speech processing skills acquired in one FL may not automatically transfer to another FL.