קדיש - בעגלא ובזמן קריב
We find the word בעגלא only two places in the Gemara (Berachos 18b, Sanhedrin 52a) and Rashi in both places explains the word to mean מהרה, quickly. According to this the understanding of this phrase is meant to convey by saying it twice, it should happen very quickly.
However, this does not explain why a word (בעגלא) was chosen that is not well known to convey this matter of quickness. If an Aramaic word was needed (like the rest of the language of Kaddish), then the word should have been בפריע, like the Targum translates using that word both in Parshas Ekev (11, 17) ואבדתם מהרה and in Parshas Korach (17 ,11) והולך מהרה. However, we do not find anywhere else (besides the two places in Gemara cited above) that uses the world עגלא as a translation of the Hebrew word מהרה.
Therefore, perhaps one could say that this word alludes to Sanhedrin (97a) that the coming of Moshiach will occur suddenly (לפתע) in a single moment and the matter of redemption is included in the language of וימליך מלכותי. And in Mishlei (29, 1) the translation of the word לפתע is עגלא.
Thus, in Kaddish, we are requesting that Geulah should come quickly, plus, in a time that is close. Thus, Kaddish states these two phrases in order to mention two concepts: of quick method and of a time that is in a moment.
