Freddie Mac and Fannie Mae maintained a healthy appetite for interest-only mortgages during the first half of the year – a period that saw many major players split their volume among the rival GSEs, a new Inside Alternative Mortgages analysis reveals. Combined, Fannie and Freddie purchased $76.32 billion in prime IO loans during the first two months of the year. That put the GSEs on pace to obliterate the record they set in 2005,…