Wati's return to New Zealand in 2015 was initially undetected by authorities because she entered under the fraudulently obtained passport under the alias "Rukhmanny".
Wati's lawyer Jarom Keung said she had persisted in getting into the country to help a family member who was being abused and who also had mental health issues.
Wati also suffered from serious health issues from being in prison, he said.
Through Keung, Wati's family hoped she would get home detention but Judge Simon Menzies agreed with Immigration NZ counsel Aaron McIlroy's submission that the offending was serious and needed to be deterred.
McIlroy said Wati had a sense of entitlement and still protested her innocence over six previous shoplifting convictions.
Immigration New Zealand assistant general manager Peter Devoy says the dual identities came to light when Wati was asked to provide her original passport as part of the verification process for a partnership-based temporary visa application she made.
"A facial comparison between photographs of Wati and Rukhmanny indicated they were the one and same person," Devoy says.
"A subsequent fingerprint analysis corroborated the facial recognition evidence.
"The integrity of the immigration system is paramount and this type of fraud will not be tolerated. Today's sentence is a strong deterrent."
Once Wati has served her sentence she will be deported to Fiji.
Wati was also sentenced for shoplifting beauty products from a Palmerston North pharmacy in December 2011.