OK, when I said “that never happens”, I clearly didn't expect this.

• 2ac: GLASNOSTIC: Signal cost ‘varied’ in the spirit of openness: *(SIGNALCOST); ref. Glasnost
• 10ac: GOOROO: Schmaltz on jumper spelling ‘revered old teacher’: GOO (= schmaltz) + ROO (= kangaroo); variant of “guru”
• 11ac: CORNEA: Cereal crop alongside river – it's regularly grafted: CORN + EA (= river); ref. Corneal grafting
• 13ac: GORGON: What abstainers drink, reverting? It's appallingly ugly: NO GROG reversed
• 14ac: QUAINT: Stop holding ‘amateur’ as meaning ‘lovably odd’: QUINT (organ stop) around A(mateur)
• 15ac: SPIE: Not the actor? That is what Marlowe doubled as possibly: THESP (= actor) - THE + IE; ref. Christophe Marlowe
• 16ac: PURPOSE: Turned up poser solved, the desired goal: UP reversed + *(POSER)
• 20ac: EITHER: Solvent? I admitted it may introduce an alternative: ETHER (solvent) around I
• 21ac: RINSES: Light bathes north in upward slopes: N(orth) in RISES
• 22ac: NATANT: Swimming in Mediterranean at Antibes: mediterraneaN AT ANTibes
• 24ac: ENTRAP: Snare with associate (all but red) made to backtrack: PARTNERED - RED
• 28ac: DIAPASE: Old melody to fade with a dance coming in: DIE (= fade) around PAS (dance)
• 30ac: GLEN: Depression, often extended, a feature of singleness: sinGLENess
• 31ac: IMPARL: I unfolded map with both hands to hold a confab: I + *(MAP) + RL (both hands)
• 32ac: SHALLI: Look at these delicate fibres – do you think I should?: Double definition
• 33ac: CAPRID: E.g. angora bonnet, free?: CAP (= bonnet) + RID (= free); ref. Angora
• 34ac: SAPELE: Fine wood from Peru got in auction: PE(ru) in SALE (= auction)
• 35ac: METACENTRE: Mozart's first entr'acte composed containing English: a point of intersection: M(ozart) + *(ENTRACTE) around E(nglish): ref. Metacentre
• 1dn: EGGS BENEDICT: Binges with ged etc cooked in tasty snack: *(BINGES GED ETC)
• 2dn: GOOPY: Energy starting work with bit of yolk, glutinous: GO (= energy) + OP(us) + Y(olk)
• 3dn: LORIOT: Pretty bird, one yet to pass test with love and loose living: L (ref. L-plate) + O (love) + RIOT; var. oriole
• 4dn: SOOK: Aussie wimp, and accordingly not particularly good: SO (accordingly) + OK (not particularly good)
• 5dn: NONPARTY: Parton active in New York, unattached politically: N(ew) Y(ork) outside *(PARTON)
• 6dn: SOURCING: Finding origin of crab-apple? It includes Cuba: SOURING outside C(uba)
• 7dn: TRAPUNTO: Type of quilting made of horsecloth until obsolete: TRAP (horsecloth) + UNTO (obs. until)
• 8dn: INION: Lackey has head clipped causing lump thereon: (m)INION
• 9dn: WATER SPANIEL: Gundog that's reliant with paws galloping round heart of fen?: *(RELIANT PAWS) around fEn
• 12dn: ENSUE: To succeed it must be removed fom a bathroom: EN-SUITE - IT
• 17dn: CHAMPART: Amateur page in carriage, what feudal lord was entitled to: HAM (amateur) + P(age) in CART (carriage)
• 18dn: DENTARIA: Parasitic plant strangely radiant about end of tree: *(RADIANT) around treE
• 19dn: BRETESSE: Gallery helping the beseiged – network's replacing one in foundation: BASSE (= foundation) with A (one) replaced by RETE (= network)
• 23dn: ANIMA: A good mimic uplifted the feminine in a man: A MINA (var. myna, starling capable of imitations) reversed.
• 25dn: ROLLER: Canary, one singing, about to fly off: CAROLLER - CA (= circa, about)
• 26dn: NAPPE: Chump losing last sheet of sums: NAPPER (= head) - R
• 27dn: SELLE: E.g. palfrey's saddle, partly tasselled: tasSELLEd
• 29dn: KHAN: Dirk (Persian) pulling jar in eastern inn: KHANJAR (Persian dagger) - JAR

So there we go: two in a row.