Are three footsteps of the Aśvins and 3 steps of Vishnu as mentioned in Rig Veda the same?

 The word विष्णु - viṣṇu emanated from the root विष् - viṣ - indicating to pervade.

The pervasiveness is the quality of the formless BRAHMAN/ENERGY. Hence, viṣṇu indicates pervasiveness, including that of humans.

Rig Vedic viṣṇu’s 3 steps have nothing to do with Puranic Vamana’s 3 steps covering 3 Worlds.

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In Rig Veda 1.154.2, viṣṇu is eulogised as pervading everything.

प्र तद्विष्णुः स्तवते वीर्येण मृगो न भीमः कुचरो गिरिष्ठाः । यस्योरुषु त्रिषु विक्रमणेष्वधिक्षियन्ति भुवनानि विश्वा ॥
pra tad viṣṇuḥ stavate vīryeṇa mṛgo na bhīmaḥ kucaro giriṣṭhāḥ | yasyoruṣu triṣu vikramaṇeṣv adhikṣiyanti bhuvanāni viśvā ||

English translation:

In this way Viṣṇu will be praised for his heroic deed—(he who is) like a fearsome wild beast, living in the mountains and roaming wherever it wants, in whose three wide strides dwell all living beings.

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In Nirukta (12.1), the meaning of Aśvins was mentioned as follows:

The Aśvins are (so called) because they two pervade (अश् - ash) everything”.

Rig Veda 8.8.23

त्रीणि पदान्यश्विनोराविः सान्ति गुहा परः । कवी ऋतस्य पत्मभिरर्वाग्जीवेभ्यस्परि ॥
trīṇi padāny aśvinor āviḥ sānti guhā paraḥ | kavī ṛtasya patmabhir arvāg jīvebhyas pari ||

English translation:

There are three footsteps of the Aśvins—though being visible they are hidden far away. (Let) the two poets (drive) nearby along the flights of truth, away from (other) living beings.

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Now, a question may arise as to what the 3 steps are going to cover?

Please note that those 3 steps do not cover external worlds,ie., EARTH, SPACE and Heaven.

Those 3 worlds are within an individual SPIRITUAL realm, indicating the starting point of spirituality to attaining of SELF REALISATION.

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Hence, as both viṣṇu and Aśvins indicate pervasiveness, the three steps of viṣṇu and Aśvins indicate the same thing, ie, filling the spiritual realm of an individual.