The young men who had grown up with him [Rehoboam] replied, "Tell the people who have said to you, 'Your father put a heavy yoke on us, but make our yoke lighter' - tell them, 'My little finger is thicker than my father's waist.'"
"Tell" unnecessarily appears a second time, also in the Hebrew:
יְדַבְּרוּ אִתּוֹ הַיְלָדִים אֲשֶׁר גָּדְלוּ אִתּוֹ לֵאמֹר כֹּֽה־תֹאמַר לָעָם אֲשֶׁר־דִּבְּרוּ אֵלֶיךָ לֵאמֹר אָבִיךָ הִכְבִּיד אֶת־עֻלֵּנוּ וְאַתָּה הָקֵל מֵעָלֵינוּ כֹּה תֹּאמַר אֲלֵהֶם קָֽטָנִּי עָבָה מִמָּתְנֵי אָבִֽי׃
In the following verse, these young men advise Rehoboam to impose a heavier burden on the people, and later he follows their advice. In a way, the pleonastic "tell" reflects this increase; even in the language that these young men use, there's an abundance.
The parallel passage in 1 Kings 12:10 also contains a pleonasm, although here the two words are distinct in Hebrew:
וַיְדַבְּרוּ אֵלָיו הַיְלָדִים אֲשֶׁר גָּדְלוּ אִתּוֹ לֵאמֹר כֹּֽה־תֹאמַר לָעָם הַזֶּה אֲשֶׁר דִּבְּרוּ אֵלֶיךָ לֵאמֹר אָבִיךָ הִכְבִּיד אֶת־עֻלֵּנוּ וְאַתָּה הָקֵל מֵעָלֵינוּ כֹּה תְּדַבֵּר אֲלֵיהֶם קָֽטָנִּי עָבָה מִמָּתְנֵי אָבִֽי׃