The dvaita interpretation of this verse is that it reflects the highest meditative state of a devotee, who is in deep love and knowledge of Brahman as it comes very close and intimate with Brahman. The statement "I am Brahman" is made because the devotee thinks of nothing but Brahman.
vijayadhvajatIrtha was a later dvaita commentator on the bhAgavatam in his padaratnAvalI. It says the following on 12.5.11.
दंशदोषास्पर्शने प्रकारान्तरेणोपायमाह-अहमिति । न हन्यत इत्यहं न हीयत इति वा कदापि न जहाति स्वशक्तिमिति वा एवं विधमीश्वरं विहाय कदापि न तिष्टत्यस्वातन्त्र्यादित्यर्थः उपासनाफलमाह-एवमिति । एवंविधस्त्वं निष्कले आत्मनि परमात्मानं समाधाय संयुज्य समीक्ष्य सम्यक् ध्यायन्
I have kept the Devanagari text above because it is my own transcription, so should be checked. Here is my attempt at translating it:
daMsha- sting , doShA- night , sparshane- feel, prakArAn- section, tare- boat crossing, pAyam- water, Aha- no, aham- I am, iti- that
The feeling of a sting at night, partly crossing the water, aha, I am that.
I am a little unsure about how to translate this sentence of commentary. The writer compares himself to a sting, signifying the baseness of the self in contrast to the idea that it becomes Brahman, and only having partly crossed the ocean of samsAra: the same word tari is used for crossing samsAra in the ganga sahasranAma #400. For the dvaitin, the self is insignificant compared to Brahman, like a mosquito to a person. This statement contrasts with the view that is contradicted in the next sentence.
na hanyata ityahaM na hIyata iti vA kadApi na jahAti svashaktimiti vA evaM vidhamIshvaraM vihAya kadApi na tiShTatyasvAtantryAdityarthaH upAsanAphalamAha-evamiti
na- no, hanyata- kill, ity- thus, ahaM- I, na- not, hIyata- extinguished, iti- that, vA- or, kadApi- never, na- no, jahAti- leaves, svashaktim- own power, iti- that, vA- or, evaM- such, vidham- kind, IshavaraM- god, vihAya- having left, kadApi- never, na- no, tiShTa- constant, tya- roaming, svA- self, tantry- by tantra, Aditya- deity , arthaH- object of desire, upAsanA- worship, phalam- reward acc, Aha- not, evam- like, iti- this
Thus that self (“I”) is not killed; that is never extinguished or leaves its own power, or never becomes like a kind of god, having left. No, the reward for worship is not like this: [becoming a] constantly roaming self, deity [and] object of desire using tantra.
So the dvaita interpretation of this verse is that the self always remains after liberation, not being deified.
evaMvidhastvaM niShkale Atmani paramAtmAnaM samAdhAya saMyujya samIkShya samyak dhyAyan
evaM- such, vidha- kind, tvam- you, niShkale- undivided, Atmani- in the soul, paramAtmAnaM- who is the supersoul, samAdh- having focused, Aya- thus, saMyujya- intimacy, samIkShya- having investigated, samyak- wholly, dhyAyan- lost in meditation
In such a kind of undivided soul, you having focused [ on the one who is] the supersoul, thus [there is] intimacy, having investigated wholly and [being] lost in meditation.