Of plurals and singulars

As part of the process of producing the priestly vestements, פסוק כ"ח:מ commands "ולבני אהרן תעשה כתנות", and for the sons of Aharon you shall make tunics. This can be interpreted in two ways - one tunic for each כהן or many tunics for each כהן. This is the subject of a dispute in ירושלמי יומא ג:ו. The רבנן hold two tunics for each כהן and ר' יוסי holds one tunic for each כהן suffices.

In the .גמרא מגילה ז we find רב יוסף learns that when it says in מתנות לאביונים in מגילת אסתר it means 2 total מתנות for 2 אביונים - only one for each poor person. טורי אבן in חגיגה and אבני שהם in מגילה (same author) comment that this גמרא goes like ר' יוסי in the ירושלמי who holds one tunic for each כהן. However, asks מצפה איתן in מגילה, from תוספות in .חגיגה ג we see that the הלכה in regards to the dispute in the ירושלמי is like the רבנן - two tunics for each כהן. If רב יוסף in מגילה is going only according to ר' יוסי then it is not in accordance with הלכה!

מצפה איתן answers from פרי חדש אורח חיים תרצ"ד who writes that if the פסוק had written "ולאביונים מתנות" then it would have implied two to each but now that it says it the other way around it only means one to each. Therefore, the rule is that if the subject is written before the object then it may imply that to these subjects you will give (plural) objects to each. That then is the subject of dispute in ירושלמי where the פסוק in question is "ולבני אהרן תעשה כתנות", the subject coming before the object. However, with מתנות לאביונים where the object comes first, it means that these objects shall be distributed amongst the following subjects and everyone will agree that it is one per person. [This also explains why the גמרא in יומא entertains the possibility that there were two lots on each goat in the יום כפור procedure because the pasuk is "על שני השעירים גורלות," the subject before the object.]