I'm afraid we couldn't reproduce this. We made a blockchain using bitcoin parameters, got a new address using getnewaddress, then creating a multisig in the wallet as follows:
addmultisigaddress 2 '["15Tis1TyWZ3xHf4XS4nvf79iLGmQ9C7twm","1JoeB7kfwqUyDBURHFymta3qP6Nt4UhrfA"]'
Here's what's shown for the multisig in listaddresses with verbose=true :
{
"address" : "3BRFKrSm1Qgvbg56Xmaw37NpFJupxMNK1d",
"ismine" : true,
"iswatchonly" : false,
"isscript" : true,
"script" : "multisig",
"hex" : "522103a238e2047b3659ed11e07d7291178b263004b73f3459b1d2168e52fb5d0774d621030792853eb924b82b8f325a90deeaaf9748625e690620aba153eab8123caf958252ae",
"addresses" : [
"15Tis1TyWZ3xHf4XS4nvf79iLGmQ9C7twm",
"1JoeB7kfwqUyDBURHFymta3qP6Nt4UhrfA"
],
"sigsrequired" : 2,
"account" : "",
"synchronized" : false,
"startblock" : 5
}