Siman 105
Presented here for study, not as a practical ruling. The Shulchan Aruch rules by Sephardi custom, the Rema's glosses by Ashkenazi custom, and the Kitzur follows Ashkenazi custom. For a practical question, ask your rabbi.
א הַמִּתְפַּלֵּל שְׁתֵּי תְּפִלּוֹת, זוֹ אַחַר זוֹ, צָרִיךְ לְהַמְתִּין בֵּין זוֹ לָזוֹ כְּדֵי הִלּוּךְ ד' אַמּוֹת, כְּדֵי שֶׁתְּהֵא דַּעְתּוֹ מְיֻשֶּׁבֶת לְהִתְפַּלֵּל בִּלְשׁוֹן תְּחִנָּה.
1 The Law Of One Who Prays Two [Amidah] Prayers. Containing 1 Se'if: One who prays two [Amidah] prayers, one after the other, must wait between one and the other [for the time it takes] to walk 4 amot, so that one's understanding may be settled, [in order] to pray with the language of supplication.