In the transition of Persian from Old Persian (OP) to Middle (MP) and finally New Persian (NP), there is a significant phonemic change: reduction of VCV to V (V = vowel; C = consonant). That is to say, VCV reduces to either V's of VCV and consequently, C and the other V disappear:

Avestan or Old Persian Middle Persian New Persian
shiyâti shâti —> shâdi shâdi
chavant chant —> chand chand
duvar dar dar
khshâyathiya shâha —> shâh shâh

New Persian being more than 1100 years old, has also experienced this pattern. There are many reductions both in the standard dialect and regional dialects. Interestingly, in some dialects a different V has been picked out, resulting in having, for example, «minam» and «monam» from «mikonam».

Before After Before After
mishavam misham nevardebâm nardebâm
miravam miram khwâhar khwâr
mikhwâham mikhwâm pirâhan piran
midaham midam barâdar barâr
mitavânam mitânam —> mitunam khâsiye [1] khâye
miguyam migam, migum khodemun khomun
miyâvaram miyâram    
miyâyam miyâm    
migozâram mizâram
mikonam minam, monam
mibinam minam
midânam minam
rafte budam raftudam

[1] This phonemic rule can help us in retrieving the older form of words. I found khâsiye in a dictionary about the dialect spoken in Shahr e Bâbak and its neighboring regions. khâsiye should be the older form of khâye.