Цитата: nthnI can't find ANY information about it. All info will be greatly appreciated. Thanks.
I mirrored (and cropped) the second image; nice token (can I buy it ?!).
EDIT: I found straight away that second image, like your reverse ...
http://collections.rmg.co.uk/collections/objects/37847.html
as I typed medal PETRVS Neptune MDCCII in a Search.
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Details (from the item in National Maritime Museum, Greenwich, London):
Commemorating the Capturing of Shlisselburg.
RUSSIA, Tsardom of Rus. Petr I Alekseyevich Veliky (Peter the Great). 1682-1725.
Medal (47mm, 48.70 g, 12h).
Obverse: Bust of Czar Peter I, laureate, in armour (cuirassed) and draped in a cloak (right).
Legend:
PETRVS . ALEXII . FIL . D . G . RVSS . IMP . M . DVX MOSCOVIÆ
Reverse: Storming of the fortifications at Nöteborg, batteries in foreground; Neptune reclining right, holding a trident in right hand, and a key in left, lying below.
Legend:
NOTTEBVRGVM . NVNC . SCHLVSSELBVRGUM
(Once Nöteborg, now Shlisselburg)
Exergue (three lines):
POST . ANN . XC . ABHOSTB . RECVP . D . XII OCTOB S V MDCCII
(After 90 years, recovered from the enemies after on the 12th of October, O.S.)
The Artist: T. Iwanov (Timophey Ivanov)
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Although, with you saying you had found one with a different reverse, I see that one has a different obverse; as portrait and lettering are slightly different. Also the one I found is different metal. But it does show most of what it was made for, and dated MDCCII (1702) and made in 1703 to commemorate the battle.
Trying to see what yours has on it; something like ...
Legend:
PETRVS . ALEXEEWITZ . M . D . TZAR . M . D . MOSCOV .
(PETER, SON OF ALEXEY,
M D, TSAR, GREAT DUKE OF MOSCOW)
The underlined meaning unknown, and second M D is M. DVX. abbreviated. Maybe >
(Peter, son of Alexey, by the Grace of God, great Tsar and Grand Duke of Moscow)
which I found somewhere, but D G is Dei Gratia (by the Grace of God), and not M D letters?
The first link below has these excerpts, about two-thirds down the long page >
The Great Northern War (1700-1721) and Associated Medals
The peace treaty with Turkey was signed on August 18, 1700, in Constantinople. Internal peace was thus restored, if only temporarily. Now Russia was ready for another war: this time, with the Swedish King Karl XII (Fig. 11). Russia fought the Great Northern War of 1700-1721 with Sweden to gain access to the Baltic Sea and regain control over the territories in the northwest that it had lost in 1613.
The first major victory of the Russian army against the Swedes in the north was the capture of Schlüsselburg in October 1702, under the command of B.P. Sheremetev. The reverse of the medal commemorating this event (Fig. 14) depicts the reclining figure of Neptune holding a trident and key and watching a bombardment of the city; a fortress in fire and smoke is visible in the background. The inscription in the exergue refers to the return of the territory that once belonged to Russia: POST ANN. XC. AB HOSTE | RECVP . D . XII OCTOB SV | MDCCII [AFTER NINETY YEARS TAKEN BACK FROM THE ENEMY. 12 OCTOBER (OLD STYLE) 1702].
Other links I found (from which I merged/adapted with some of the above information):
http://ansmagazine.com/Summer06/Russian
http://www.coins-and-medals.ru/medals/db/russia/peter_1/capture_schlisselburg/215_251706.shtml?en

That's about all I could find. Took me a couple of hours, so after all that maybe you could give (or sell) me the medal for my troubles!
P.S. I don't think the topic can be marked solved yet -
Different obverse image and lettering
Different metal
No idea of value (I'll pay you that $10 you paid, plus postage)